#include <bits/stdc++.h>
using namespace std;
long long n, m;
char cur[10][10], res[10][10];
long long mx;
bool lT(long long i, long long j, char x[10][10]) {
  if (i < 1 || j < 2 || i > n - 2) return 0;
  if (x[i][j] != '.' || x[i - 1][j] != '.' || x[i + 1][j] != '.' ||
      x[i][j - 1] != '.' || x[i][j - 2] != '.')
    return 0;
  return 1;
}
bool rT(long long i, long long j, char x[10][10]) {
  if (i < 1 || i > n - 2 || j > m - 3) return 0;
  if (x[i][j] != '.' || x[i - 1][j] != '.' || x[i + 1][j] != '.' ||
      x[i][j + 1] != '.' || x[i][j + 2] != '.')
    return 0;
  return 1;
}
bool dT(long long i, long long j, char x[10][10]) {
  if (i > n - 3 || j < 1 || j > m - 2) return 0;
  if (x[i][j] != '.' || x[i + 1][j] != '.' || x[i + 2][j] != '.' ||
      x[i][j + 1] != '.' || x[i][j - 1] != '.')
    return 0;
  return 1;
}
bool uT(long long i, long long j, char x[10][10]) {
  if (i < 2 || j < 1 || j > m - 2) return 0;
  if (x[i][j] != '.' || x[i - 1][j] != '.' || x[i - 2][j] != '.' ||
      x[i][j - 1] != '.' || x[i][j + 1] != '.')
    return 0;
  return 1;
}
void dfs(char now, char x[10][10], long long state) {
  if (mx < state) {
    mx = state;
    for (long long i = 0; i < n; i++)
      for (long long j = 0; j < m; j++) res[i][j] = cur[i][j];
  }
  long long cntf = 0, f = 0;
  for (long long i = 0; i < n; i++) {
    for (long long j = 0; j < m; j++) {
      if (f == 1) cntf++;
      if (cntf > 2) return;
      if (lT(i, j, x)) {
        f = 1;
        x[i][j] = x[i - 1][j] = x[i + 1][j] = x[i][j - 1] = x[i][j - 2] = now;
        dfs(now + 1, x, state + 1);
        x[i][j] = x[i - 1][j] = x[i + 1][j] = x[i][j - 1] = x[i][j - 2] = '.';
      }
      if (rT(i, j, x)) {
        f = 1;
        x[i][j] = x[i - 1][j] = x[i + 1][j] = x[i][j + 1] = x[i][j + 2] = now;
        dfs(now + 1, x, state + 1);
        x[i][j] = x[i - 1][j] = x[i + 1][j] = x[i][j + 1] = x[i][j + 2] = '.';
      }
      if (uT(i, j, x)) {
        f = 1;
        x[i][j] = x[i - 1][j] = x[i - 2][j] = x[i][j - 1] = x[i][j + 1] = now;
        dfs(now + 1, x, state + 1);
        x[i][j] = x[i - 1][j] = x[i - 2][j] = x[i][j - 1] = x[i][j + 1] = '.';
      }
      if (dT(i, j, x)) {
        f = 1;
        x[i][j] = x[i + 1][j] = x[i + 2][j] = x[i][j + 1] = x[i][j - 1] = now;
        dfs(now + 1, x, state + 1);
        x[i][j] = x[i + 1][j] = x[i + 2][j] = x[i][j + 1] = x[i][j - 1] = '.';
      }
    }
  }
}
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> m;
  for (long long i = 0; i < n; i++)
    for (long long j = 0; j < m; j++) cur[i][j] = '.';
  for (long long i = 0; i < n; i++)
    for (long long j = 0; j < m; j++) res[i][j] = '.';
  dfs('A', cur, 0);
  cout << mx << endl;
  for (long long i = 0; i < n; i++) {
    for (long long j = 0; j < m; j++) cout << res[i][j];
    cout << endl;
  }
  return 0;
}
