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 repd(i,a,b) for (int i=(a);i<(b);i++)
#define rep(i,n) repd(i,0,n)
typedef long long ll;
using namespace std;
const int MOD = 1000000007;
const int INF = 1010000000;
const double EPS = 1e-10;
const array<pair<int,int>,4> fd{make_pair(1,0),make_pair(-1,0),make_pair(0,1),make_pair(0,-1)}; 
//ll

int main(){
  string n;cin>>n;
  int ans = 0;
  rep(i,n.size())if(n[i]=='2')ans++;
  cout << ans << endl;
}