func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 50 + 5;   const int oo = 1000000000;   bool u[N][N];   int n, m;   int ans = -1;   int a[N][N], l[N][N];   int d[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};   char s[N];   struct pis {     int x, y;     pis() {}     pis(int x, int y) : x(x), y(y) {}   } f[10 * N * N];   inline int Solve(int x, int y) {     for (int i = 1; i <= n; i++)       for (int j = 1; j <= m; j++) l[i][j] = oo;     int front = 0, top = 1;     f[1] = pis(x, y);     l[x][y] = 0;     while (front < top) {       pis p = f[++front];       u[p.x][p.y] = 0;       for (int i = 0; i < 4; i++) {         int dx = p.x + d[i][0];         int dy = p.y + d[i][1];         if (dx >= 1 && dx <= n && dy >= 1 && dy <= m) {           int dis = a[p.x][p.y] != a[dx][dy];           if (l[p.x][p.y] + dis < l[dx][dy]) {             l[dx][dy] = l[p.x][p.y] + dis;             if (!u[dx][dy]) {               u[dx][dy] = 1;               f[++top] = pis(dx, dy);             }           }         }       }     }     int MAX = 0;     for (int i = 1; i <= n; i++)       for (int j = 1; j <= m; j++)         if (a[i][j] && l[i][j] > MAX) MAX = l[i][j];     return MAX;   }   int main() {     scanf( %d %d , &n, &m);     for (int i = 1; i <= n; i++) {       scanf( %s , s);       for (int j = 1; j <= m; j++) {         if (s[j - 1] ==  B ) ans = oo;         a[i][j] = s[j - 1] ==  W  ? 0 : 1;       }     }     for (int i = 1; i <= n; i++)       for (int j = 1; j <= m; j++) ans = min(ans, Solve(i, j));     printf( %d n , ans + 1);     return 0;   }   