#include <iostream>
#include <string>
using namespace std;
int main(){
	int N;
	cin >> N;
	string S;
	cin >> S;
	int ans = 0;
	for (int i = 0; i < N; i++){
		for (int k = i + 1; k < N; k++){
			if ((k - i) % 2 == 0){
				int j = (i + k) / 2;
				if (S[i] == 'U' && S[j] == 'M' && S[k] == 'G'){
					ans++;
				}
			}
		}
	}
	cout << ans << endl;
}