#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <cmath>
#include <queue>
#include <limits>
#include <iomanip>

using namespace std;

int main() {
    int n;
    int ans;
    string s;
    cin >> n;
    cin >> s;
    vector<int>M;
    for(int i = 0; i < n; i++){
        if(s[i] == 'M') M.push_back(i);
    }

    if(M.size() == 0) {
        cout << ans << endl;
        return 0;
    }

    for(int i = 0; i < M.size(); i++) {
        int center = M[i];
        int d = 1;
        while(M[i] - d >= 0 || M[i] + d < n) {
            if(s[M[i]-d] == 'U' && s[M[i]+d] =='G') ans += 1;
            d++;
        }
    }

    cout << ans << endl;
}