using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var s = ReadLine();
        var ans = 0;
        for (var i = 0; i < n; ++i)
        {
            if (s[i] != 'U') continue;
            for (var j = 1; i + j + j < n; ++j)
            {
                if (s[i + j] == 'M' && s[i + j + j] == 'G') ++ans;
            }
        }
        WriteLine(ans);
    }
}