#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < n; ++i)
#define rep3(i, l, n) for (int i = l; i < n; ++i)
#define chmax(a, b) a = max(a, b)
#define chmin(a, b) a = min(a, b)
#define out(a) cout << a << endl
#define SZ(v) (int)v.size()
#define inf (int)(1e9+7)
int main() {
    int n; string s; cin >> n >> s;
    int sum = 0;
    rep(i, n) {
        rep3(j, i + 1, n) {
            int k = 2 * j - i;
            if (k < 0 || k >= n) continue;
            if (s[i] == 'U' && s[j] == 'M' && s[k] == 'G') sum++;
        }
    }
    out(sum);
}