#include <bits/stdc++.h>
#define INF 2147483647
#define INF_LL 9223372036854775807
#define MOD 1000000007
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;

int main() {
	int N; string S;
	cin >> N >> S;
	int ans = 0;
	for (int i = 0; i < N; i++) {
		for (int j = 1; j < N; j++) {
			if (i + j * 2 >= S.size())continue;
 			if (S[i] == 'U' && S[i + j] == 'M' && S[i + j * 2] == 'G')ans++;
		}
	}
	cout << ans << endl;
}