func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m;   int r1, c1, r2, c2;   char s[505][505];   bool dfs(int i, int j) {     if (r2 == i && c2 == j && s[r2][c2] !=  . ) return 1;     if (s[i][j] !=  . ) return 0;     s[i][j] =  X ;     return dfs(i + 1, j) || dfs(i - 1, j) || dfs(i, j + 1) || dfs(i, j - 1);   }   int main() {     cin >> n >> m;     for (int i = 1; i <= n; i++)       for (int j = 1; j <= m; j++) cin >> s[i][j];     cin >> r1 >> c1 >> r2 >> c2;     s[r1][c1] =  . ;     if (dfs(r1, c1))       cout <<  YES  << endl;     else       cout <<  NO  << endl;     return 0;   }   