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++14 (Clang 3.8.0) (judge verdict: Accepted)

#include <iostream>
using namespace std;
int main(void)
{
    int n;
    int ans = 0;
    cin >> n;
    while (n / 10 != 0)
    {
        if (n % 10 == 2)
        {
            ans++;
        }
        n /= 10;
    }
    if (n % 10 == 2)
    {
        ans++;
    }
    cout << ans << endl;
}