Problem:
Score : 200 points

Problem Statement

We have A cards, each of which has an integer 1 written on it. Similarly, we also have B cards with 0s and C cards with -1s.

We will pick up K among these cards. What is the maximum possible sum of the numbers written on the cards chosen?

Constraints

All values in input are integers.

0 \leq A, B, C

1 \leq K \leq A + B + C \leq 2 \times 10^9

Input

Input is given from Standard Input in the following format:

A B C K

Output

Print the maximum possible sum of the numbers written on the cards chosen.

Sample Input 1

2 1 1 3

Sample Output 1

2

Consider picking up two cards with 1s and one card with a 0.
In this case, the sum of the numbers written on the cards is 2, which is the maximum possible value.

Sample Input 2

1 2 3 4

Sample Output 2

0

Sample Input 3

2000000000 0 0 2000000000

Sample Output 3

2000000000

Solution in Scala (2.13.1) (judge verdict: Accepted)

object Main extends App {
  val inputs: Seq[String] = scala.io.Source.stdin.getLines().toList
  val nums = inputs(0).split(" ").map(_.toInt)
  val a = nums(0)
  val b = nums(1)
  val c = nums(2)
  val k = nums(3)

  println(solve(a, b, c, k))

  def solve(a: Int, b: Int, c: Int, k: Int): Int = {
    var ans = 0

    if(k < a) {
      ans = k
    } else if (k <= a + b) {
      ans = a
    } else {
      val tmpK = k - (a + b)
      ans = a + (tmpK * -1)
    }
    return ans
  }
}