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: Wrong Answer)

const TEST = `6 2 3 4`
// A B C K

// inputに入力データ全体が入る
function Main(input) {
  const inputArr = input.trim().split(" ");
  let countA = parseInt(inputArr[0])
  let countB = parseInt(inputArr[1])
  let countK = parseInt(inputArr[3])
  let res = 0
  countK = countK - countA
  res = countK > countA ? res + countA : countA
  if (0 >= countK) {
    console.log(res)
    return;
  }
  countK = countK - countB
  if (0 >= countK) {
    console.log(res)
    return;
  }
  res = res - countK
  console.log(res)
}
// Main(TEST)

//*この行以降は編集しないでください（標準入出力から一度に読み込み、Mainを呼び出します）
Main(require("fs").readFileSync("/dev/stdin", "utf8"));