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>
#include <stdlib.h>

int main()
{
   int A,B,C,K;
   scanf("%i %i %i %i",&A,&B,&C,&K);

   if(K<=A){
    printf("%i\n",(K*1));
   }
   else if((K>=A)&&(K<=A+B)){
     printf("%i\n",((A*1)+(K-A)*0));
   }
   else if((K>=A+B)&&(K<=A+B+C)){
    printf("%i\n",((A*1)+(B*0)+((K-A-B)*(-1))));
   }

    return 0;
}