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

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

    long long ans = 0;
    for(int i=0;i<N;i++){
        for(int j=i+1;j<N;j++){
            int k = 2*j-i;
            if(k < 0 || k > N-1) continue;
            if(S[i] == 'U' && S[j] == 'M' && S[k] == 'G') ans++;
        }
    }

    cout << ans << endl;

}