#include <iostream>
using namespace std;
int main(){
    int n;cin>>n;
    string s;cin>>s;
    int ans = 0;
    for(int i = 0; n > i; i++){
        if(s[i] != 'M')continue;
        for(int j = 1; 0 <= i-j && i+j < n; j++){
            if(s[i-j] == 'U' && s[i+j] == 'G')ans++;
        }
    }
    cout << ans << endl;
}