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

int main() {
  int n;
  string s;
  cin >> n >> s;
  int cnt = 0;
  for (int i = 0; i < n; i++) {
    if (s[i] == 'M') {
      for (int j = 1; j <= min(n - i, i); j++) {
        if (s[i - j] == 'U' && s[i + j] == 'G') {
          cnt++;
        }
      }
    }
  }
  cout << cnt << endl;
  return 0;
}