#include "bits/stdc++.h"
#define in std::cin
#define out std::cout
#define rep(i,N) for(LL i=0;i<N;++i)
typedef long long int LL;

int main()
{
	LL N;
	std::string S;
	in >> N >> S;

	LL ans = 0;
	rep(i, N)
	{
		for (LL j = i + 1; j < N; ++j)
		{
			LL k = j + (j - i);
			if (k >= N) continue;
			if (S[i] == 'U'&&S[j] == 'M'&&S[k] == 'G') ++ans;
		}
	}
	out << ans << std::endl;
}