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)

// *3 or /2

#include <iostream>
#include <cmath>
#include <vector>
#include <algorithm>
#include <unordered_map>
#include <ios>
#include <iomanip>
#include <string>
#include <numeric>

using namespace std;

int n;

int main() {
    cin >> n;

    int res = 0;
    while (n > 0) {
        if (n % 10 == 2) {
            res++;
        }
        n /= 10;
    }

    cout << res << endl;

    return 0;
}