#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  int n;
  cin >> n;
  string s;
  cin >> s;
  int ans = 0;
  for (int i = 0; i < n; i++) {
    if (s[i] == 'M') {
      for (int j = 1; j < n; j++) {
        if (i - j < 0 || i + j >= n) break;
        ans += s[i - j] == 'U' && s[i + j] == 'G';
      }
    }
  }
  cout << ans << endl;
  return 0;
}