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 <cstdio>
#include <vector>
#include <set>
#include <unordered_set>
#include <cmath>
#include <algorithm>
#include <numeric>
#include <cassert>
#include <utility>

using namespace std;
using lli = long long int;
// #define DEBUG
#ifdef DEBUG
#define debug(var) cout << (#var) << ": " << (var) << endl;
template<class T> void dump_array_impl(const T& a) {
  bool first = true;
  for (auto&& x : a) {
    if (!first) { cout << ", "; first = false; }
    cout << x;
  }
}
#define debug_array(a) cout<<(#a)<<": ";dump_array_impl(a);cout<<endl
#else
#define debug(var) {}
#define debug_array(a) {}
#endif
template<class T> void read_n(vector<T>& v, size_t n) {
  v = vector<T>(n);
  for (lli i=0; i<n; ++i) cin >> v[i];
}


int main() {
  string s;
  cin >> s;
  int ans=0;
  for (auto c:s) ans += c=='2' ? 1 : 0;
  cout << ans << endl;
  return 0;
}