using System;

namespace yukicoder
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine();
            bool f = false;
            bool f1 = false;
            int count = 0;
            for (int i = 0; i < s.Length; i++)
            {
                string b = s.Substring(i, 1);

                if ( b == "n" )
                {
                    count++;               
                }
            }
            Console.WriteLine(count);
        }
    }
}