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