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 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <cmath>
#include <algorithm>
#include <functional>
#include <stack>
#include <queue>
#include <string>
#include <map>
#include <unordered_map>
#include <bitset>
#include <numeric>
#include <vector>
#include <unordered_set>
#include <bitset>
#include <limits>
#include <random>
#include <complex>
#include <numeric>
#include <cstdlib>


using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;

const ll mod=1000000007ll;
const ll inf=1000000000000000ll;


int main(){
    ll k,s,ans;
    cin>>k>>s;
    ans=0;
    for(ll i=0;i<=k;i++){
        for(ll j=0;j<=k;j++){
                if(s-(i+j)<=k&&0<=s-(i+j))ans++;
        }
    }
    cout<<ans<<endl;

    return 0;
}