#include<bits/stdc++.h>
using namespace std;
int main(){
  int N;
  cin>>N;
  string S;
  cin>>S;
  long long count=0;
  for(int i=0;i<=N-1;i++){
    for(int j=i+1;j<=N-1;j++){
      if(S[i]=='U'&&S[j]=='M'&&S[2*j-i]=='G')count++;
    }
  }
  cout<<count<<endl;
}