Problem:
Score : 200 points

Problem Statement

You are given two integers K and S.

Three variable X, Y and Z takes integer values satisfying 0≤X,Y,Z≤K.

How many different assignments of values to X, Y and Z are there such that X + Y + Z = S?

Constraints

2≤K≤2500

0≤S≤3K

K and S are integers.

Input

The input is given from Standard Input in the following format:

K S

Output

Print the number of the triples of X, Y and Z that satisfy the condition.

Sample Input 1

2 2

Sample Output 1

6

There are six triples of X, Y and Z that satisfy the condition:

X = 0, Y = 0, Z = 2

X = 0, Y = 2, Z = 0

X = 2, Y = 0, Z = 0

X = 0, Y = 1, Z = 1

X = 1, Y = 0, Z = 1

X = 1, Y = 1, Z = 0

Sample Input 2

5 15

Sample Output 2

1

The maximum value of X + Y + Z is 15, achieved by one triple of X, Y and Z.

Solution in Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"fmt"

)

func main() {
	var k, s int
	fmt.Scanf("%d %d", &k, &s)

	count := 0

	for x := 0; x <= k; x++ {
		for y := x; y <= k; y++ {
			for z := y; z <= k; z++ {
				if s == x + y + z {
					switch compare(x, y, z) {
					case "three":
						count++
					case "two":
						count += 3
					case "diff":
						count += 6
					}
				}
			} 
		}
	}
}

func compare(x, y, z int) string {
	if z == y || y == x {
		if z == x {
			return "three"
		}
		return "two"
	}
	return "diff"
}