#define _GLIBCXX_DEBUG
#define ll long long
#define INF 1000000000;
#define INF_B 1000000000000000000;
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

int main(){
  int N; cin >> N;
  string S; cin >> S;
  int ans = 0;
  for(int i = 0; i < (int)S.size()-2; i++){
    if(S[i] == 'U'){
      for(int j = i+2; j < (int)S.size(); j += 2){
        if(S[(i+j)/2] == 'M' and S[j] == 'G') ans++;
      }
    }
  }
  cout << ans << endl;
}