diff --git "a/hyeokbini/1025.\354\240\234\352\263\261\354\210\230 \354\260\276\352\270\260/1025.cpp" "b/hyeokbini/1025.\354\240\234\352\263\261\354\210\230 \354\260\276\352\270\260/1025.cpp"
new file mode 100644
index 0000000..443848e
--- /dev/null
+++ "b/hyeokbini/1025.\354\240\234\352\263\261\354\210\230 \354\260\276\352\270\260/1025.cpp"	
@@ -0,0 +1,67 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int dx[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
+int dy[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
+int ans = -1;
+
+void check(int val)
+{
+    int root = (int)sqrt(val);
+    if (root * root == val && ans < val)
+    {
+        ans = val;
+    }
+    return;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(0);
+    //freopen("test.txt", "rt", stdin);
+    int n, m;
+    cin >> n >> m;
+    vector<vector<int>> arr(n, vector<int>(m));
+    for (int i = 0; i < n; i++)
+    {
+        string tmp;
+        cin >> tmp;
+        for (int j = 0; j < m; j++)
+        {
+            arr[i][j] = tmp[j] - '0';
+        }
+    }
+    // 시작 위치 지정
+    for (int i = 0; i < n; i++)
+    {
+        for (int j = 0; j < m; j++)
+        {
+            // 한칸 단위도 체크
+            check(arr[i][j]);
+            for (int mulx = -n; mulx <= n; mulx++)
+            {
+                for (int muly = -m; muly <= m; muly++)
+                {
+                    if (mulx == 0 && muly == 0)
+                    {
+                        continue;
+                    }
+                    int curx = i;
+                    int cury = j;
+                    int tempval = 0;
+                    while (curx < n && curx >= 0 && cury < m && cury >= 0)
+                    {
+                        tempval *= 10;
+                        tempval += arr[curx][cury];
+                        check(tempval);
+                        curx += mulx;
+                        cury += muly;
+                    }
+                }
+            }
+        }
+    }
+    cout << ans;
+}
\ No newline at end of file
diff --git a/hyeokbini/README.md b/hyeokbini/README.md
index ed8dc8d..182728a 100644
--- a/hyeokbini/README.md
+++ b/hyeokbini/README.md
@@ -22,3 +22,4 @@
  | 18차시 | 2025.08.07 |  브루트포스  | [약속 장소](https://www.acmicpc.net/problem/25542)|[#18](https://github.com/AlgoLeadMe/AlgoLeadMe-15/pull/66)|
  | 19차시 | 2025.08.10 |  브루트포스  | [리모컨](https://www.acmicpc.net/problem/1107)|[#19](https://github.com/AlgoLeadMe/AlgoLeadMe-15/pull/68)|
  | 20차시 | 2025.08.14 |  완전탐색,DFS  | [모음사전](https://school.programmers.co.kr/learn/courses/30/lessons/84512)|[#20](https://github.com/AlgoLeadMe/AlgoLeadMe-15/pull/72)|
+ | 21차시 | 2025.08.19 |  브루트포스  | [제곱수 찾기](https://www.acmicpc.net/problem/1025)|[#21](https://github.com/AlgoLeadMe/AlgoLeadMe-15/pull/76)|