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 "vector"
#include "string"
#include "algorithm"
#include "math.h"
using namespace std;
 
int main()
{
  int n;
  cin >> n;
  int ans = 0;
  while (n != 0)
  {
    if (n % 10 == 2)
    {
      ans++;
    }
    n /= 10;
  }
  cout << ans << "\n";
}