#include <bits/stdc++.h>
using namespace std;
const int a1[4][5] = {{0, 1, 2, 2, 2},
                      {0, 1, 1, 1, 2},
                      {0, 0, 0, 1, 2},
                      {0, 1, 1, 1, 2}},
          a2[4][5] = {{1, 1, 0, 1, 2},
                      {2, 0, 1, 2, 2},
                      {0, 1, 2, 1, 1},
                      {0, 0, 1, 2, 0}};
int i, j, k, n, m, ff[10][10], an, re[10][10];
void dfs(int x, int y, int z, int s) {
  if (z + (m * (n - x)) / 5 <= an) return;
  if (x + 2 > n) {
    if (an < z) {
      an = z;
      memcpy(re, ff, sizeof(re));
    }
    return;
  }
  if (y + 2 > m) {
    dfs(x + 1, 1, z, s);
    return;
  }
  int i, j, xx, yy;
  for (i = 0; i <= 3; i++) {
    int F = 0;
    for (j = 0; j <= 4; j++) {
      xx = x + a1[i][j], yy = y + a2[i][j];
      if (ff[xx][yy]) {
        F = 1;
        break;
      }
    }
    if (F) continue;
    for (j = 0; j <= 4; j++) {
      xx = x + a1[i][j], yy = y + a2[i][j];
      ff[xx][yy] = z + 1;
    }
    dfs(x, y + 1, z + 1, s - 5);
    for (j = 0; j <= 4; j++) {
      xx = x + a1[i][j], yy = y + a2[i][j];
      ff[xx][yy] = 0;
    }
  }
  dfs(x, y + 1, z, s - 1);
}
int main() {
  scanf("%d%d", &n, &m);
  dfs(1, 1, 0, n * m);
  printf("%d\n", an);
  for (i = 1; i <= n; i++) {
    for (j = 1; j <= m; j++)
      printf("%c", !re[i][j] ? '.' : char(re[i][j] + 64));
    printf("\n");
  }
  return 0;
}
