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 (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<stdlib.h>
#include<limits.h>

#define rep(i,begin,end) for(int i=begin; i<end; i++)
#define revrep(i,begin,end) for(int i=begin; i>end; i--)
#define lld long long int

int main(){
    int n, cnt = 0;
    scanf("%d", &n);
    while(n>0){
        if(n % 10 == 2){
            cnt++;
        }
        n /= 10;
    }
    printf("%d", cnt);

    return 0;
}