Problem:
Score : 100 points

Problem Statement

You are given an integer N that has exactly four digits in base ten.
How many times does 2 occur in the base-ten representation of N?

Constraints

1000 \leq N \leq 9999

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer.

Sample Input 1

1222

Sample Output 1

3

2 occurs three times in 1222. By the way, this contest is held on December 22 (JST).

Sample Input 2

3456

Sample Output 2

0

Sample Input 3

9592

Sample Output 3

1

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;

class Program
{
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int cnt = 0;

            while(n > 0)
            {
                if(n%10 == 2)
                    cnt++;
                n /= 10;
            }

            Console.WriteLine(cnt);

        }
}