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 JavaScript (Node.js 12.16.1) (judge verdict: Accepted)


function Main(input) {
    input = input.trim();
    input = input.split(" ")

    var a = parseInt(input[0])
    var b = parseInt(input[1])
    var c = parseInt(input[2])
    var d = parseInt(input[3])

    if (d <= a) {
        console.log(d)
    } else {
        if (d <= a + b) {
            console.log(a)
        } else {
            console.log(a - (d - (a + b)))
        }
    }
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));