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)


// Problem : B - Easy Linear Programming
// Contest : AtCoder - AtCoder Beginner Contest 167
// URL : https://atcoder.jp/contests/abc167/tasks/abc167_b
// Memory Limit : 1024 MB
// Time Limit : 2000 ms
// Powered by CP Editor (https://github.com/cpeditor/cpeditor)

//Totka hai dosto
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll

int32_t main()
{
	int a,b,c,k;
	cin>>a>>b>>c>>k;
	
	int ans=0;
	int rem=k;
	
	ans+=min(a,rem);
	rem-=min(a,rem);
	if(rem==0)
	{
		cout<<ans;return 0;
	}
	ans+=(min(b,rem)*0);
	rem-=min(b,rem);
	if(rem==0)
	{
		cout<<ans;return 0;
	}
	ans-=min(rem, c);
	cout<<ans;
}