//Normal

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

void print(auto a){
  cout << a;
}

void prints(auto a){
  cout << a << " ";
}

void prints(){
  cout << " ";
}

void printl(auto a){
  cout << a << endl;
}

void printl(){
  cout << endl;
}

void fix(int n){
  cout << fixed << setprecision(n);
}

int siz(string s){
  return (int)s.size();
}

int main(){
  int N; cin >> N;
  string S; cin >> S;

  int ans = 0;
  int F = (int)S.find("M");
  while(F != -1){
    int i = 1;

    while(F-i >= 0 and F+i < N){
      if(S[F-i] == 'U' and S[F+i] == 'G') ans++;

      i++;
    }

    S[F] = '-';

    F = (int)S.find("M");
  }

  print(ans);

  return 0;
}