#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ul = unsigned long;
using ull = unsigned long long;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	ll n;
	string s;
	cin >> n >> s;

	vector<int> u, m;
	set<int> g;
	for (int i = 0; i < n; ++i)
	{
		if (s[i] == 'U')
			u.push_back(i);
		else if (s[i] == 'M')
			m.push_back(i);
		else if (s[i] == 'G')
			g.insert(i);
	}

	ll res{ 0 };
	for (const auto& itu : u)
	{
		for (auto itm =m.crbegin();itm!=m.crend();++itm)
		{
			if (itu > *itm)
				break;
			int k = *itm * 2 - itu;
			if (g.count(k))
				++res;
		}
	}

	cout << res << "\n";

	return 0;
}