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 Scala (2.11.7) (judge verdict: Accepted)

import scala.io.StdIn

object Main {

  def main(args: Array[String]): Unit = {

    val n: Int = StdIn.readLine().toInt
    println(solve(n))

  }

  def solve(n: Int): Int = {

    if (n == 0) {
      0
    } else if (n % 10 == 2) {
      solve(n / 10) + 1
    } else {
      solve(n / 10)
    }

  }

}