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: Time Limit Exceeded)

#include <stdio.h>

//if文多くてコード汚いのどうにかしたいけれど、そんな技術は生憎持ち合わせていない

int main(){
  int a,b,c,k;
  scanf("%d%d%d%d",&a,&b,&c,&k);
  
  int max = 0;
  for(int i=k; i>0; i--){
    if(a>0){
      max += 1;
      a--;
    }else{
      if(b>0){
        max += 0;
        b--;
      }else{
        if(c>0){
          max -= 1;
          c--;
        }
      }
    }
  }
  printf("%d",max);
}