#include "bits/stdc++.h"

using namespace std;

void solve()
{
	int n, ans = 0;
	string s;
	cin >> n >> s;
	for (int x = 1; x <= n/2; x++)
	{
		for (int i = 0; i < n; i++)
		{
			int j = i + x, k = j + x;
			if (j < n && k && n)
			{
				bool ok = 1;
				ok &= s[i] == 'U';
				ok &= s[j] == 'M';
				ok &= s[k] == 'G';
				ans += ok;
			}
		}
	}
	cout << ans << endl;
}

int main(void)
{
	solve();
	//cout << "yui(*-v・)yui" << endl;
	return 0;
}