diff --git a/GeeksForGeeks/January/30-1-24/GFG.java b/GeeksForGeeks/January/30-1-24/GFG.java
new file mode 100644
index 0000000..b2a7196
--- /dev/null
+++ b/GeeksForGeeks/January/30-1-24/GFG.java
@@ -0,0 +1,62 @@
+//{ Driver Code Starts
+//Initial Template for Java
+import java.io.*;
+import java.util.*; 
+class GFG{
+    public static void main(String args[]) throws IOException 
+    { 
+        BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
+        int t = Integer.parseInt(read.readLine());
+        while(t-- > 0){
+            String input_line[] = read.readLine().trim().split("\\s+");
+            int n1 = Integer.parseInt(input_line[0]);
+            int n2 = Integer.parseInt(input_line[1]);
+            int n3 = Integer.parseInt(input_line[2]);
+            input_line = read.readLine().trim().split("\\s+");
+            String A = input_line[0];
+            String B = input_line[1];
+            String C = input_line[2];
+            Solution obj = new Solution();
+            System.out.println(obj.LCSof3(A, B, C, n1, n2, n3));
+        }
+    } 
+} 
+// } Driver Code Ends
+
+
+//User function Template for Java
+class Solution 
+{ 
+    static int help(String A,String B,String C,int i,int j,int k,int n1,int n2,int n3,int dp[][][])
+    {
+            if(i==n1 || j==n2 || k==n3)
+                return 0;
+            if(dp[i][j][k]!=-1)
+                return dp[i][j][k];
+            if(A.charAt(i)==B.charAt(j) && A.charAt(i)==C.charAt(k))
+            {
+                return dp[i][j][k]=1+help(A,B,C,i+1,j+1,k+1,n1,n2,n3,dp);
+            }
+            
+            int a = help(A,B,C,i+1,j,k,n1,n2,n3,dp);
+            int b = help(A,B,C,i,j+1,k,n1,n2,n3,dp);
+            int c = help(A,B,C,i,j,k+1,n1,n2,n3,dp);
+            
+            return dp[i][j][k]= Math.max(a,Math.max(b,c));
+    }
+    
+    
+    int LCSof3(String A, String B, String C, int n1, int n2, int n3) 
+    { 
+        // code here
+        int dp[][][] = new int[n1][n2][n3];
+        for(int temp[][]:dp)
+        {
+            for(int temp2[]:temp)
+            {
+                Arrays.fill(temp2,-1);
+            }
+        }
+        return help(A,B,C,0,0,0,n1,n2,n3,dp);
+    }
+}
diff --git a/GeeksForGeeks/January/30-1-24/README.md b/GeeksForGeeks/January/30-1-24/README.md
new file mode 100644
index 0000000..4654edf
--- /dev/null
+++ b/GeeksForGeeks/January/30-1-24/README.md
@@ -0,0 +1,2 @@
+Time complexity - O(n1 * n2 * n3)
+Space complexity - O(n1 * n2 * n3)
diff --git a/GeeksForGeeks/January/31-1-24/GFG.java b/GeeksForGeeks/January/31-1-24/GFG.java
new file mode 100644
index 0000000..ac4772f
--- /dev/null
+++ b/GeeksForGeeks/January/31-1-24/GFG.java
@@ -0,0 +1,106 @@
+//{ Driver Code Starts
+// Initial Template for Java
+
+/*package whatever //do not write package name here */
+
+import java.io.*;
+import java.util.*;
+class GFG {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        int t = sc.nextInt();
+
+        while (t-- > 0) {
+            int n = sc.nextInt();
+            sc.nextLine();
+            String[] keys = sc.nextLine().split(" ");
+
+            TrieNode root = new TrieNode();
+            for (int i = 0; i < n; i++) {
+                insert(root, keys[i]);
+            }
+            String abc = sc.nextLine();
+            if (search(root, abc))
+                System.out.println(1);
+            else
+                System.out.println(0);
+        }
+    }
+
+    static final int ALPHABET_SIZE = 26;
+
+    // trie node
+    static class TrieNode {
+        TrieNode[] children = new TrieNode[ALPHABET_SIZE];
+
+        // isEndOfWord is true if the node represents
+        // end of a word
+        boolean isEndOfWord;
+
+        TrieNode() {
+            isEndOfWord = false;
+            for (int i = 0; i < ALPHABET_SIZE; i++) children[i] = null;
+        }
+    };
+
+    
+// } Driver Code Ends
+// User function Template for Java
+
+/*
+static final int ALPHABET_SIZE = 26;
+
+    // trie node
+    static class TrieNode {
+        TrieNode[] children = new TrieNode[ALPHABET_SIZE];
+
+        // isEndOfWord is true if the node represents
+        // end of a word
+        boolean isEndOfWord;
+
+        TrieNode() {
+            isEndOfWord = false;
+            for (int i = 0; i < ALPHABET_SIZE; i++) children[i] = null;
+        }
+    };
+*/
+//Function to insert string into TRIE.
+static void insert(TrieNode root, String key) 
+{
+    // Your code here
+    TrieNode curr = root;
+    for(int level=0; level<key.length(); level++)
+    {
+        int idx = key.charAt(level)-'a';
+        if(curr.children[idx] == null)
+        {
+            curr.children[idx] = new TrieNode();
+        }
+        curr = curr.children[idx];
+    }
+    curr.isEndOfWord = true;
+}
+
+
+//Function to use TRIE data structure and search the given string.
+static boolean search(TrieNode root, String key)
+{
+    // Your code here
+    TrieNode curr = root;
+    for(int level=0; level<key.length(); level++)
+    {
+        int idx = key.charAt(level)-'a';
+        if(curr.children[idx] == null)
+        {
+            return false;
+        }
+        curr = curr.children[idx];
+    }
+    return curr.isEndOfWord == true;
+}
+
+
+//{ Driver Code Starts.
+}
+// } Driver Code Ends
diff --git a/GeeksForGeeks/January/31-1-24/README.md b/GeeksForGeeks/January/31-1-24/README.md
new file mode 100644
index 0000000..99cc3f3
--- /dev/null
+++ b/GeeksForGeeks/January/31-1-24/README.md
@@ -0,0 +1,2 @@
+Time complexity - O(m)
+Space complexity - O(m)
diff --git a/LeetCode/January/30-1-24/README.md b/LeetCode/January/30-1-24/README.md
new file mode 100644
index 0000000..7384c4b
--- /dev/null
+++ b/LeetCode/January/30-1-24/README.md
@@ -0,0 +1,2 @@
+Time complexity - O(n)
+Space complexity - O(n)
diff --git a/LeetCode/January/30-1-24/Solution.java b/LeetCode/January/30-1-24/Solution.java
new file mode 100644
index 0000000..d326f04
--- /dev/null
+++ b/LeetCode/January/30-1-24/Solution.java
@@ -0,0 +1,30 @@
+class Solution 
+{
+    public int evalRPN(String[] tokens) 
+    {
+        final Map<String, BinaryOperator<Long>> op = Map.of(
+                                "+", (a, b) -> a + b,
+                                "-", (a, b) -> a - b, 
+                                "*", (a, b) -> a * b, 
+                                "/", (a, b) -> a / b);
+
+        
+        Deque<Long> stack = new ArrayDeque<>();
+
+        for (final String token : tokens)
+        {
+            if (op.containsKey(token)) 
+            {
+                long b = stack.pop();
+                long a = stack.pop();
+                stack.push(op.get(token).apply(a, b));
+            }
+            else 
+            {
+                stack.push(Long.parseLong(token));
+            }
+        }
+
+        return stack.pop().intValue();
+    }
+}
diff --git a/LeetCode/January/31-1-24/README.md b/LeetCode/January/31-1-24/README.md
new file mode 100644
index 0000000..7384c4b
--- /dev/null
+++ b/LeetCode/January/31-1-24/README.md
@@ -0,0 +1,2 @@
+Time complexity - O(n)
+Space complexity - O(n)
diff --git a/LeetCode/January/31-1-24/Solution.java b/LeetCode/January/31-1-24/Solution.java
new file mode 100644
index 0000000..4e2873b
--- /dev/null
+++ b/LeetCode/January/31-1-24/Solution.java
@@ -0,0 +1,21 @@
+class Solution 
+{
+    public int[] dailyTemperatures(int[] temperatures) 
+    {
+        int[] ans = new int[temperatures.length];
+        Deque<Integer> stack = new ArrayDeque<>(); // a decreasing stack
+
+        for (int i = 0; i < temperatures.length; ++i) 
+        {
+            while (!stack.isEmpty() && temperatures[stack.peek()] < temperatures[i]) 
+            {
+                int index = stack.pop();
+                ans[index] = i - index;
+            }
+            
+            stack.push(i);
+        }
+
+        return ans;
+    }
+}