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 <bits/stdc++.h> 
 
#define INF (1<<31)//INT_MAX/2
#define MOD 1000000007
 
using ll  = long long;
using ull = unsigned long long;
 
int main(int argc, char *argv[])
{
    std::string s;
    std::cin >> s;
    int count = 0;
    if (s[0] == '2') {
        count++;
    }
    if (s[1] == '2') {
        count++;
    }
    if (s[2] == '2') {
        count++;
    }
    if (s[3] == '2') {
        count++;
    }

    std::cout << count << std::endl;
    return 0;
}