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)

function Main(input) {
	var str = input;
	var ans = 0;
	str = str.split("\n")[0];
	str = str.split(" ");
	var a = Number(str[0]);
	var b = Number(str[1]);
	var c = Number(str[2]);
	var k = Number(str[3]);
	ans = Number(ans);
	if (a <= k){
	ans = ans + a;
	k = k - a;
   	}
	k = k - b;
	if(k > 0){
	ans = ans - k;
	}
   console.log(ans);
}
 //*おまじない
Main(require("fs").readFileSync("/dev/stdin", "utf8"));