using System;

public class Program
{
    public static void Main()
    {
        _ = Console.ReadLine();
        var value = Console.ReadLine();
        var ct = 0;
        for (var i = 0; i < value.Length; i++){
            if (value[i] == 'U'){
                for (var j = i + 1; j < value.Length; j++){
                    if (value[j] == 'M' && value.Length > (2 * j - i) && value[2 * j - i] == 'G')
                        ct++;
                }
            }
        }
        Console.Write("{0}", ct);
        return;
    }
}