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 Go (1.14.1) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"math"
	"os"
	"strconv"
	"strings"
)

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Scan()
	params := strings.Split(scanner.Text(), " ")
	paramA, _ := strconv.ParseInt(params[0], 10, 64)
	paramB, _ := strconv.ParseInt(params[1], 10, 64)
	paramC, _ := strconv.ParseInt(params[2], 10, 64)
	paramK, _ := strconv.ParseInt(params[3], 10, 64)
	result := math.Min(float64(paramA), float64(paramK))
	paramK -= paramA
	paramK -= paramB
	if paramK > 0 {
		result -= math.Min(float64(paramC), float64(paramK))
	}
	print(int(result))
}