#include <bits/stdc++.h>
using namespace std;
char s[106];
long long dp[55][2], ans = 1;
bool vis[106], ok[106];
void init() {
  dp[1][0] = dp[1][1] = 1;
  for (int i = 2; i <= 50; i++) {
    dp[i][0] = dp[i - 1][0] + dp[i - 1][1];
    dp[i][1] = dp[i - 1][0];
  }
}
int main() {
  init();
  scanf("%s", s + 1);
  int n = strlen(s + 1);
  if (n == 1) return 0 * printf("0\n");
  for (int i = 1; i <= n; i++) {
    int nex = i + 1;
    if (nex > n) nex -= n;
    if (s[i] == 'B' && s[nex] == 'A') vis[i] = 1;
  }
  for (int h = 1; h <= n; h++) {
    for (int i = 1; i <= n; i++) {
      if (vis[i]) {
        int nex1 = i + 1, nex2 = i + 2, las1 = i - 1, las2 = i - 2, cnt = 2;
        if (nex1 > n) nex1 -= n;
        if (nex2 > n) nex2 -= n;
        if (las1 < 1) las1 += n;
        if (las2 < 1) las2 += n;
        if (s[nex2] == 'B' && !vis[nex2])
          vis[i] = 0, ok[i] = 1, s[i] = 'A', s[nex1] = 'B';
        if (s[las1] == 'A' && !vis[las2])
          vis[i] = 0, ok[i] = 1, s[i] = 'A', s[nex1] = 'B';
      } else {
        int nex1 = i + 1, nex2 = i + 2;
        if (nex1 > n) nex1 -= n;
        if (nex2 > n) nex2 -= n;
        if (!vis[nex2] && !ok[nex1] && s[nex1] == 'A' && s[nex2] == 'B')
          return 0 * printf("0\n");
      }
    }
  }
  int cnt2 = 0;
  for (int i = 1; i <= n; i++) {
    int cnt = 0, las2 = i - 2, f = i;
    if (las2 < 1) las2 += n;
    if (vis[las2]) {
      cnt2++;
      continue;
    }
    if (vis[f]) {
      while (vis[f]) {
        cnt++;
        f += 2;
        if (f > n) f -= n;
      }
    }
    if (cnt == 0) continue;
    ans *= dp[cnt][0] + dp[cnt][1];
  }
  if (cnt2 * 2 == n) {
    if (cnt2 == 1)
      ans += 1;
    else if (cnt2 == 2)
      ans += 3;
    else
      ans *= dp[cnt2 - 1][0] + dp[cnt2 - 1][1] + dp[cnt2 - 2][0];
  }
  printf("%lld\n", ans);
  return 0;
}
