#include <bits/stdc++.h>
using namespace std;

int main() {
  int N;
  string S;
  cin >> N >> S;
  int ans = 0;
  for (int m = 0; m < N; m++)
    if (S.at(m) == 'M')
      for (int u = 0, g; u < m; u++)
        if (S.at(u) == 'U' && (g = m + (m - u)) < N && S.at(g) == 'G') ans++;
  cout << ans << "\n";
}