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>
#include <stdlib.h>


int main (void){
  int a,b,c,k;
  int suml=0;


  int i; 
  if ( scanf("%d %d %d %d",&a,&b,&c,&k) == 4){
    if ( k - a >= 0) {
      k-=a;
      suml +=a;
    }else if ( k - 1 >= 0) {
      for(i=0; i<a; i++){
	if ( k - 1 >=0 ) {
	  k--;
	  suml += 1;
	}
      }}
    
    if ( k - b >= 0) k -=b;
    else if ( k-1 >= 0){
      for(i=0; i<b; i++){
	if ( k - 1 >=0 ) {
	  k--;
	}
      }}

    if ( k - c >= 0) suml -=c;
    else if ( k-1 >= 0){
      for(i=0; i<c; i++){
	if ( k - 1 >=0 ) {
	  k--;
	  suml -= 1;
	}
      }}
   
    printf("%d\n",suml);
  }
    

    
  return 0;
  
}