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: Time Limit Exceeded)

#pragma region ヘッダー
#define _CRT_SECURE_NO_WARNINGS

#ifdef _____MY_DEBUG_____
#define VS_ENDPAUSE()	(system("pause"))
#define DEBUG_OUT(...)  (printf(__VA_ARGS__))
#else
#define VS_ENDPAUSE()
#define DEBUG_OUT(...)
#endif

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <math.h>
#include <cmath>
#include <vector>
#include <algorithm>
#include <string>

using namespace std;
typedef signed char int8;
typedef signed short int16;
typedef signed int int32;
typedef signed long long int64;
typedef unsigned char uint8;
typedef unsigned short uint16;
typedef unsigned int uint32;
typedef unsigned long long uint64;
#define int int64

#ifndef INT8_MIN
#define INT8_MIN	(-127)
#endif
#ifndef INT8_MAX
#define INT8_MAX	( 128)
#endif
#ifndef UINT8_MAX
#define UINT8_MAX	( 255)
#endif
#ifndef INT16_MIN
#define INT16_MIN	(-32768)
#endif
#ifndef INT16_MAX
#define INT16_MAX	( 32767)
#endif
#ifndef UINT16_MAX
#define UINT16_MAX	( 65535)
#endif
#ifndef INT32_MIN
#define INT32_MIN	(-2147483648)	// -2 * 10^9
#endif
#ifndef INT32_MAX
#define INT32_MAX	( 2147483647)	//  2 * 10^9
#endif
#ifndef UINT32_MAX
#define UINT32_MAX	( 4294967295)	//  4 * 10^9
#endif
#ifndef INT64_MIN
#define INT64_MIN	(-9223372036854775808)	// -9 * 10^18
#endif
#ifndef INT64_MAX
#define INT64_MAX	( 9223372036854775807)	//  9 * 10^18
#endif
#ifndef UINT64_MAX
#define UINT64_MAX	( 18446744073709551615)	// 18 * 10^18
#endif

void func(void);
#pragma endregion

int32 main(void)
{
    func();
    VS_ENDPAUSE();
    return 0;
}


void func(void)
{
//DEBUG_OUT("----\n");
    uint32 K, S;
    cin >> K >> S;

    uint32 ans = 0;
    for(uint32 x=0; x<=K; x++){
        if(x+K+K < S){ continue; }
        for(uint32 y=0; y<=(S-x) && y<=K; y++){
            if(x+y+K < S){ continue; }
            for(uint32 z=0; z<=(S-x-y) & z<=K; z++){
                if(x+y+z == S){
                    DEBUG_OUT("x=%d y=%d z=%d\n", x, y, z);
                    ans ++;
                }
            }
        }
    }

    cout << ans << endl;
    
    return;
}