using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace yukicoder_481 {
    class Program {
        static void Main(string[] args) {
            string[] s = Console.ReadLine().Split(' ');
            int[] t = new int[s.Length];
            int count = 0;
            for (int i = 0; i < s.Length; i++) {
                t[i] = int.Parse(s[i]);
                if (t[i] != i + 1) {
                    count++;
                }
            }
            Console.WriteLine(10 - count);
            Console.ReadLine();
        }
    }
}