#include <iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<map>
#include<cstdio>
using namespace std;

int main(){
	int n;
	cin >> n;
	string s;
	cin >> s;
	int l = 0;
	for (int i = 0; i < n-2; i++) {
		for (int j = 0; j < n - 1; j++) {
			for (int k = 0; k < n; k++) {
				if (j - i == k - j>0&&s[i] == 'U'&&s[j] == 'M'&&s[k] == 'G') {
					l += 1;
				}
			}
		}
	}
	cout << l << endl;
	return 0;
}