#include <iostream>
#include <algorithm>
#include <vector>
#include <string>

using namespace std;

int main() {
  int N;
  string S;
  cin >> N >> S;
  int ans = 0;
  for (int i = 0; i < N; i++) {
    for (int j = 1; i + 2 * j < N; j++) {
      if (S[i] == 'U' && S[i + j] == 'M' && S[i + 2 * j] == 'G') {
        ans++;
      }
    }
  }
  cout << ans << '\n';
}