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 C (GCC 5.4.1) (judge verdict: Time Limit Exceeded)

#include <stdio.h>

int main(void) {
	int k, s;
	int x, y, z;
	int counter = 0;
	scanf("%d %d", &k, &s);
	for (x=0; x<=k; x++) {
		if (!(x<=s)) break;
		for (y=0; y<=k; y++) {
			if (!(x+y<=s)) break;
			for (z=0; z<=k; z++) {
				if (!(x+y+z<=s)) break;
				if (x+y+z==s) counter++;
			}
		}
	}
	printf("%d\n", counter);

	return 0;
}