diff --git a/hadongun/README.md b/hadongun/README.md
index 2db4390..02d568e 100644
--- a/hadongun/README.md
+++ b/hadongun/README.md
@@ -18,5 +18,6 @@
  | 14차시| 2025.05.20 |  트리  | [트리의 부모 찾기] (https://www.acmicpc.net/problem/11725)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/56|
  | 15차시| 2025.05.21 |  트리  | [트리] (https://www.acmicpc.net/problem/1068)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/58|
  | 16차시| 2025.06.27 |  구현  | [킹] (https://www.acmicpc.net/problem/1063)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/68|
- | 17차시| 2025.07.04 |  두 포인터  | [두 수의 합] (https://www.acmicpc.net/problem/3273)||
+ | 17차시| 2025.07.04 |  두 포인터  | [두 수의 합] (https://www.acmicpc.net/problem/3273)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/71|
+ | 18차시| 2025.07.08 |  그래프 탐색  | [헌내기는 친구가 필요해] (https://www.acmicpc.net/problem/21736)||
  ---
\ No newline at end of file
diff --git "a/hadongun/\355\203\220\354\203\211/\355\227\214\353\202\264\352\270\260\353\212\224 \354\271\234\352\265\254\352\260\200 \355\225\204\354\232\224\355\225\264.py" "b/hadongun/\355\203\220\354\203\211/\355\227\214\353\202\264\352\270\260\353\212\224 \354\271\234\352\265\254\352\260\200 \355\225\204\354\232\224\355\225\264.py"
new file mode 100644
index 0000000..d377b9b
--- /dev/null
+++ "b/hadongun/\355\203\220\354\203\211/\355\227\214\353\202\264\352\270\260\353\212\224 \354\271\234\352\265\254\352\260\200 \355\225\204\354\232\224\355\225\264.py"	
@@ -0,0 +1,44 @@
+import sys
+from collections import deque
+
+def selflocation(campus, n, m):
+    result = (0,0)
+    for i in range(n):
+        for j in range(m):
+            if campus[i][j] =='I':
+                result = (i,j)
+    return result
+    
+
+def exploration(campus, n, m, s):
+    visited = [[False]*m for _ in range(n)]
+    directions = ((1, 0), (-1, 0), (0, 1), (0, -1))
+    q = deque()
+    q.append(s)
+    result = 0
+    while q:
+        y, x = q.popleft()
+        visited[y][x] = True
+        for dx, dy in directions:
+            ny, nx = y + dy, x + dx
+
+            if 0 <= ny <= n-1 and 0 <= nx <= m-1:
+                if campus[ny][nx] != 'X' and not visited[ny][nx]:
+                    visited[ny][nx] = True
+                    q.append((ny, nx))
+                    if campus[ny][nx] == 'P':
+                        result += 1
+    return result
+                
+input = sys.stdin.readline
+n, m = map(int, input().split())
+
+campus = [['']*m for _ in range(n)]
+for i in range(n):
+    campus[i] = list(input().strip())
+start = selflocation(campus, n, m)
+friend = exploration(campus, n, m, start)
+if friend == 0:
+    print('TT')
+else:
+    print(friend)