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: Accepted)

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<limits.h>

int main(void){
    int K, S;
    scanf("%d %d", &K, &S);
    int x, y, z;
    int count = 0;
    for(x=0; x<=K; x++) {
        for(y=x; y<=K; y++) {
            for(z=y; z<=K; z++) {
                if(x + y + z == S) {
                    if(x==y && y==z) {
                        count++;
                    }
                    else if((x!=y || y!=z) && ((x==y && y!=z) || (y==z && x!=y))) { 
                        count +=3;
                    }
                    else {
                        count +=6;
                    }
                }
            }
        }
    }
    printf("%d\n", count);
    return 0;
}