#include <bits/stdc++.h>
using namespace std;
#define rep(i, m, n) for (int i = m; i < n; ++i)
#define rem(i, m, n) for (int i = m; i >= n; --i)
typedef long long ll;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }

int main() {
  int N;
  string S;
  cin >> N >> S;
  ll ans = 0;
  rep(i, 1, N - 1) {
    if(S[i] == 'M') {
      rep(j, 1, N) {
        if(i - j < 0 || i + j >= N) break;
        if(S[i - j] == 'U' && S[i + j] == 'G') ans++;
      }
    }
  }
  cout << ans << endl;
  return 0;
}