#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <sstream>
#include<set>
#include<stack>

//#include<bits/stdc++.h>


using namespace std;



int main() {
	
	int t;
	cin >> t;
	string p;
	cin >> p;
	int n = p.size();
	int ans = 0;
	for (int i = 0; i < n; i++) {
		if (p[i] != 'U')continue;
		for (int j = i + 1; j < n; j++) {
			if (p[j] != 'M')continue;
			int x = j - i;
			if (j + x >= n)break;
			if (p[j + x] == 'G')ans++;

		}
	}
	cout << ans << endl;;

	return 0;


		
}