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;

namespace CADDi_2018_for_Beginners
{
    class Class1
    {
        public static void Main()
        {
            string n = Console.ReadLine();

            int result = 0;

            int value = int.Parse(n);

            int n1 = (value % 10); value /= 10; // 1桁目を取り出す
            int n2 = (value % 10); value /= 10; // 2桁目を取り出す
            int n3 = (value % 10); value /= 10; // 3桁目を取り出す
            int n4 = (value % 10); value /= 10;　// 4桁目を取り出す

            if(n1 == 2)
            {
                result += 1;
            }
            if (n2 == 2)
            {
                result += 1;
            }
            if (n3 == 2)
            {
                result += 1;
            }
            if (n4 == 2)
            {
                result += 1;
            }

            // output
            Console.WriteLine(result);
            Console.ReadLine();
        } 


    }
}