#include <bits/stdc++.h>
using namespace std;

int main()
{
	int N;
	string S;
	cin >> N >> S;

	int ans = 0;
	int n = (N + 2) / 3;
	for( int d = 1; d <= n; d++ ) {
		for( int i = 0; i < N - d * 2; i++ ) {
			int j = i + d;
			int k = j + d;
			if( S[i] == 'U' && S[j] == 'M' && S[k] == 'G' ) ans++;
		}
	}

	cout << ans << endl;
}