#include <iostream>
#include <vector>
#include <map>
#include <unordered_map>
#include <limits>
#include <algorithm>
#include <queue>
#include <set>
#include <unordered_map>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <stack>
#include <string>
#include <functional>
using namespace std;

using i64 = long long;
using ui64 = unsigned long long;

using P = pair<int, int>;

constexpr int INF = (1 << 30);
constexpr std::int64_t INF64 = (1LL << 60);
constexpr int MOD = 1e9 + 7;
constexpr double PI = 3.141592653589;

int dx[] = { -1, 0, 1, 0 };
int dy[] = { 0, 1, 0, -1 };

template <typename T, typename U>
static inline std::vector<U> makeNdVector(T n, U val) noexcept {
	static_assert(std::is_integral<T>::value, "[makeNdVector] 1st argument must be an integer type");
	return std::vector<U>(std::forward<T>(n), std::forward<U>(val));
}

template <typename T, typename ...Args>
static inline decltype(auto) makeNdVector(T n, Args... args) noexcept {
	static_assert(std::is_integral<T>::value, "[makeNdVector] 1st argument must be an integer type");
	return std::vector<decltype(makeNdVector(std::forward<Args>(args)...))>(std::forward<T>(n), makeNdVector(std::forward<Args>(args)...));
}

template <typename T>
void print(vector<T> vec)
{
	for (auto &e : vec)
		cout << e << " ";
	cout << endl;
}

void YES(bool f) { cout << (f ? "YES" : "NO") << endl; }
void Yes(bool f) { cout << (f ? "Yes" : "No") << endl; }
void yes(bool f) { cout << (f ? "yes" : "no") << endl; }

template <typename T>
T gcd(T x, T y) {
	if (x == 0 || y == 0) return 0;
	T r;
	while ((r = x % y) != 0) {
		x = y;
		y = r;
	}
	return y;
}

template <typename T>
T lcm(T x, T y) {
	if (x == 0 || y == 0) return 0;
	return (x / gcd(x, y) * y);
}

int next_combination(int sub)
{
	int x = sub & -sub, y = sub + x;
	return (((sub & ~y) / x) >> 1) | y;
}

std::uint64_t combination(int n, int r) {
	if (n < 0 || r < 0) return 0;
	if (n < r) return 0;
	std::uint64_t k = 1;
	for (std::uint64_t d = 1; d <= r; ++d) {
		k *= n--;
		k /= d;
	}
	return k;
}

signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	using P = pair<int, int>;

	int N; cin >> N;
	string S; cin >> S;
	i64 ans = 0;
	for (int i = 0; i < S.length(); ++i) {
		if (S[i] == 'U') {
			for (int j = i + 1; j < S.length(); ++j) {
				if (S[j] == 'M') {
					int k = j + (j - i);
					if (k >= S.length()) break;
					else if (S[k] == 'G') ans++;
				}
			}
		}
	}

	cout << ans << endl;
}