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: Runtime Error)

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

namespace Caddi2018
{
    class Program
    {
        static void Main(string[] args)
        {
            var obj = new Q2();
            obj.Solver();
        }
    }
    class Q2
    {

        class AB
        {
            public int A { get; set; }
            public int B { get; set; }
        }
        public void Solver()
        {
            var buf = Console.ReadLine().Split().Select(int.Parse).ToArray();

            var N = buf[0];
            var H = buf[1];
            var W = buf[2];

            var AB = new List<AB>();
            for (int i = 0; i < N; i++)
            {
                buf = Console.ReadLine().Split().Select(int.Parse).ToArray();
                AB.Add(new AB { A = buf[0], B = buf[1] });
            }

            var count = AB.Count(x => x.A >= H && x.B >= W);
            Console.WriteLine(count);

        }
    }

    //class Q1
    //{
    //    public void Solver()
    //    {
    //        var str = Console.ReadLine();

    //        Console.WriteLine(str.Count(s => s == '2'));

    //    }
    //}
}