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++14 (Clang 3.8.0) (judge verdict: Time Limit Exceeded)

#include<iostream>
using namespace std;

int main(){
  int K,S;
  cin >> K >> S;
  int x=0,y,z,expected,ans=0;
  while(x<=K){
    y=0;
    while(y<=K){
      expected = S - x - y;
      for(z=0;z<=K;z++){
        ans += expected == z;
      }
      y++;
    }
    x++;
  }
  cout << ans << endl;
}