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 C (GCC 9.2.1) (judge verdict: Accepted)

#include <stdio.h>

int main(void)
{
	int cardA, cardB, cardC, numberOfCards;
	int sum;
	int Ai, Ci;

	scanf("%d", &cardA);
	scanf("%d", &cardB);
	scanf("%d", &cardC);
	scanf("%d", &numberOfCards);

	sum = 0;

	for (Ai = 0; Ai < cardA && Ai < numberOfCards; Ai++)
	{
		sum++;
	}

	for (Ci = 0; Ci < cardC && Ci + cardA +cardB < numberOfCards; Ci++)
	{
		sum--;
	}

	printf("%d\n", sum);

	return 0;
}