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: Wrong Answer)

#include<stdio.h>

int main(){
   int a,b,c,k,i,sum=0,C=0;
   scanf("%d %d %d %d",&a,&b,&c,&k);
   int  sub = k-a;
   if(0<=a&&0<=b&&0<=c){
      if(1<=k&&k<=a+b+c&&a+b+c<=2*pow(10,9)){
         for(i=b;i<sub-b;i++){
            b++;
         }
         for(i=sub-b;i>0;i--){
            C++;
         }
         sum=a+(b*0)+(C*(-1));
         printf("%d",sum);
      }
   }
   return 0;
}