func_code_string: #include <bits/stdc++.h>   int xx[4][5] = {       {0, 0, 0, 1, 2}, {0, 1, 1, 1, 2}, {0, 1, 2, 2, 2}, {0, 1, 1, 1, 2}};   int yy[4][5] = {       {0, 1, 2, 1, 1}, {2, 0, 1, 2, 2}, {1, 1, 0, 1, 2}, {0, 0, 1, 2, 0}};   struct num {     int x, y, z;   };   int l[(20 * 20 * 25)], r[(20 * 20 * 25)], d[(20 * 20 * 25)], u[(20 * 20 * 25)],       c[(20 * 20 * 25)], add[(20 * 20 * 25)], s[(20 * 20)], tmp[(20 * 20)];   num o[100], name[(20 * 20 * 25)], best[100];   int bb[20][20];   char out[20][20];   int n, m, i, j, k, i1, len = 0, ans = 0, ss = 0;   int bo;   inline int calc(int x, int y) { return (x - 1) * m + y; }   void remove(int x) {     l[r[x]] = l[x];     r[l[x]] = r[x];     for (int i = d[x]; i != x; i = d[i]) {       for (int j = r[i]; j != i; j = r[j]) {         u[d[j]] = u[j];         d[u[j]] = d[j];         s[c[j]]--;         ss++;       }     }   }   void resume(int x) {     for (int i = u[x]; i != x; i = u[i])       for (int j = l[i]; j != i; j = l[j]) {         u[d[j]] = j;         d[u[j]] = j;         s[c[j]]++;         ss++;       }     l[r[x]] = x;     r[l[x]] = x;   }   void dfs(int t) {     if (ss > 400000000) return;     if (bo) return;     if (!r[0]) {       if (t >= ans) {         memcpy(best, o, sizeof(o));         bo = 1;       }       return;     }     int x = 0, min = 100000, num = 0;     for (int i = r[0]; i; i = r[i]) {       if (s[i] < min) min = s[i], x = i;       num++;     }     if (num / 5 + t + 1 <= ans) return;     remove(x);     for (int i = d[x]; i != x; i = d[i]) {       for (int j = r[i]; j != i; j = r[j]) remove(c[j]);       if (add[i] == 1) o[t + 1] = name[i];       dfs(t + add[i]);       for (int j = l[i]; j != i; j = l[j]) resume(c[j]);     }     resume(x);   }   int main() {     scanf( %d%d , &n, &m);     for (i = 1; i <= n; i++)       for (j = 1; j <= m; j++) {         r[len] = len + 1;         ++len;         l[len] = len - 1;         c[len] = len;         tmp[len] = len;         add[len] = 1;         s[len] = 1;       }     for (i = 1; i <= n - 2; i++)       for (j = 1; j <= m - 2; j++)         for (k = 0; k < 4; k++)           for (i1 = 0; i1 < 5; i1++) {             int x = i + xx[k][i1], y = j + yy[k][i1];             ++len;             add[len] = 1;             name[len].x = i;             name[len].y = j;             name[len].z = k;             s[calc(x, y)]++;             c[len] = calc(x, y);             if (i1 == 0)               l[len] = len + 4;             else               l[len] = len - 1;             if (i1 == 4)               r[len] = len - 4;             else               r[len] = len + 1;             u[len] = tmp[calc(x, y)];             d[tmp[calc(x, y)]] = len;             tmp[calc(x, y)] = len;           }     for (i = 1; i <= n; i++)       for (j = 1; j <= m; j++) {         len++;         c[len] = calc(i, j);         r[len] = l[len] = len;         u[len] = tmp[calc(i, j)];         d[tmp[calc(i, j)]] = len;         u[calc(i, j)] = len;         d[len] = calc(i, j);         s[calc(i, j)]++;       }     for (ans = 0; ans <= 100; ans++) {       bo = 0;       ss = 0;       dfs(0);       if (ss >= 400000000) {         ans++;         break;       }       if (!bo) break;     }     ans--;     if (ans < 0) ans = 0;     printf( %d n , ans);     for (i = 1; i <= ans; i++)       for (j = 0; j < 5; j++)         bb[best[i].x + xx[best[i].z][j]][best[i].y + yy[best[i].z][j]] = i;     for (i = 1; i <= n; i++)       for (j = 1; j <= m; j++) {         if (bb[i][j] == 0)           out[i][j] =  . ;         else           out[i][j] =  A  + bb[i][j] - 1;       }     for (i = 1; i <= n; i++) {       for (j = 1; j <= m; j++) printf( %c , out[i][j]);       printf(  n );     }     return 0;   }   