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 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <string>
#include <vector>
#include <set>
#include <stack>
#include <functional>
#define ll long long
using namespace std;


int main()
{
	cin.tie(0);
	ios::sync_with_stdio(false);
    int n;
    cin >> n;
    int cnt = 0;
    while (n > 0) {
        if ((n%10) == 2) {
            cnt++;
        }
        n /= 10;
    }
    cout << cnt << endl;
	return 0;
}