using System;
using System.Collections.Generic;
class Program
    {
    	static void Main(string[] args)
    	{
    		int n = int.Parse(Console.ReadLine());
            string s = Console.ReadLine();
            int ans = 0;
            for (int i=0; i<n-2; i++){
                if(s[i] != 'U') continue;
                for (int j = 1; i + 2 * j < n; j++)
                {
                    if (s[i + j] != 'M') continue;
                    if (s[i + 2 * j] != 'G') continue;
                    ans++;
                }
            }
            Console.WriteLine(ans);
        }
    }
    //mcs Main.cs
    //mono Main.exe