#include<bits/stdc++.h>

using namespace std;
using ll = long long;


int main()
{
	int n;
	string s; cin >> n >> s;

	int cnt = 0;

	for(int i = 0; i < n; i++) {
		for(int j = i+1; j < n; j++) {
			int k = j + (j - i);
			if(s[i] == 'U' && s[j] == 'M' && s[k] == 'G')cnt++;
		}
	}
	cout << cnt << endl;
}