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)

let input = require("fs").readFileSync("/dev/stdin", "utf8").split("\n")[0].split(' ').map(i => parseInt(i))

const A = input[0]
const B = input[1]
const C = input[2]

// const ABC = [
//     [1, input[0]],
//     [0, input[1]],
//     [-1, input[2]]
// ]
const K = input[3]

count = 0
result = 0

if (K - count - A >= 0) {
    count += A
    result += A * 1
} else {
    console.log(K)
    return
}

if (K - count - B >= 0) {
    count += B
    result += B * 0
} else {
    console.log(result)
    return
}

result += (K - count) * (-1)

console.log(result)