#include <iostream>
using namespace std;
using ll = long long;

int main()
{
    int ans = 0, n;
    string s;
    cin >> n >> s;
    for (int i = 0; i < n; i++)
    {
        for (int j = i + 1; j < n; j++)
        {
            int k = 2 * j - i;
            if (k >= n || k < j || k < i)
                continue;
            if (s[i] == 'U' && s[j] == 'M' && s[k] == 'G')
                ans++;
        }
    }
    cout << ans << endl;
}