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 Kotlin (1.3.71) (judge verdict: Wrong Answer)

fun main (args:Array<String>){
    val (a , b , c , k) = readLine()!!.split(" ").map(String::toInt)
    var maxVal = 0
    if(a < k) {
        maxVal += a * 1
//        print(maxVal)
        if(b > k - a || b == k - a) {
            maxVal += (k - a) * 0
            if(b < k - a){
//            print((k - a - b) * -1)
                maxVal += (k - a - b) * -1
                print(maxVal)
            }
            print(maxVal)
        }
    }
    // OK
    if(a == k || a > k){
        maxVal += a * 1
        print(maxVal)
    }
}