#include <bits/stdc++.h>
using namespace std;
const long long N = 110;
long long dp[N][2], n, val[N], ans;
char s[N];
signed main() {
  scanf("%s", s + 1);
  n = strlen(s + 1);
  for (long long i = 1; i <= n; ++i) val[i] = (s[i] == 'A');
  dp[1][val[1]] = 1;
  dp[0][0] = 1;
  for (long long i = 2; i <= n; ++i) {
    if (val[i]) {
      dp[i][1] += dp[i - 1][0] + dp[i - 1][1];
      if (!val[i - 1] && i != 2) dp[i][0] += dp[i - 2][0] + dp[i - 2][1];
    } else
      dp[i][0] += dp[i - 1][0];
  }
  if (val[1])
    ans += dp[n][0] + dp[n][1];
  else {
    ans += dp[n][0];
    if (val[2]) {
      memset(dp, 0, sizeof dp);
      dp[2][0] = 1;
      for (long long i = 3; i <= n; ++i) {
        if (val[i]) {
          dp[i][1] += dp[i - 1][0] + dp[i - 1][1];
          if (!val[i - 1] && i != 2) dp[i][0] += dp[i - 2][0] + dp[i - 2][1];
        } else
          dp[i][0] += dp[i - 1][0];
      }
      ans += dp[n][0] + dp[n][1];
    }
  }
  memset(dp, 0, sizeof dp);
  if (val[1] == 1 && val[n] == 0) {
    dp[1][0] = 1;
    for (long long i = 2; i < n; ++i) {
      if (val[i]) {
        dp[i][1] += dp[i - 1][0] + dp[i - 1][1];
        if (!val[i - 1]) dp[i][0] += dp[i - 2][0] + dp[i - 2][1];
      } else
        dp[i][0] += dp[i - 1][0];
    }
    ans += dp[n - 1][0] + dp[n - 1][1];
  }
  cout << ans << endl;
  return 0;
}
