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<bits/stdc++.h>
	#define LL long long

	using namespace std;

	int main(){

	  LL a,b,c,k,sum=0,kb;

	  cin>>a>>b>>c>>k;
	  
	  	if(k<=a){
	  		if(k==a)
	  			sum= (a)*1;
	  		if(k<a)
	  			sum=(a-k)*1;
	  	}else{
	  		sum = a*1;
	  		kb=k-a;
	  		if(kb>0 && kb<=b){
	  			kb=(kb-b);	
	  		}
	  		if(kb>0 && kb<=c)
					sum+=(kb)*(-1);

	  		

	  	}

	  	cout<<sum;
	  


	  return 0;
	}