#include <iostream>
#include <string>
using namespace std;

int main(){
  int N;
  cin >> N;
  string S;
  cin >> S;
  int cnt = 0;

  int width = 1;
  while(width <= N/2){
    for(int i = 0;i < N;i++){
      if(i + 2 * width > N)break;
      else{
        if(S[i] == 'U' && S[i+width] == 'M' && S[i+2*width] == 'G')cnt++;
      }
    }
    width++;
  }

  cout << cnt << endl;

}