#include<iostream>
#include<algorithm>
using namespace std;
using lint=int64_t;

int main()
{
	int N;
	string S;

	cin >> N;
	cin >> S;

	lint ans=0;
	for(int i=0;i<S.size();i++)
	{
		for(int j=i+1;j<S.size();j++)
		{
			if(S[i]=='U' && S[j]=='M')
			{
				if(2*j-i<(int)S.size() && S[2*j-i]=='G')
					ans++;
			}
		}
	}

	cout << ans << endl;
	return 0;
}