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 2147483647
#define INF_LL 9223372036854775807
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;

int main() {
	string N;
	cin >> N;
	int ans = 0;
	for (int i = 0; i < N.length(); i++)if (N[i] == '2')ans++;
	cout << ans << endl;
	return 0;
}