Problem:
Score : 200 points

Problem Statement

Snuke has come to a store that sells boxes containing balls. The store sells the following three kinds of boxes:

Red boxes, each containing R red balls

Green boxes, each containing G green balls

Blue boxes, each containing B blue balls

Snuke wants to get a total of exactly N balls by buying r red boxes, g green boxes and b blue boxes.
How many triples of non-negative integers (r,g,b) achieve this?

Constraints

All values in input are integers.

1 \leq R,G,B,N \leq 3000

Input

Input is given from Standard Input in the following format:

R G B N

Output

Print the answer.

Sample Input 1

1 2 3 4

Sample Output 1

4

Four triples achieve the objective, as follows:

(4,0,0)

(2,1,0)

(1,0,1)

(0,2,0)

Sample Input 2

13 1 4 3000

Sample Output 2

87058

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using static System.Console;
using static System.Math;

namespace AtCodeeeer
{
    class AtCOOOOOOOOOOOder
    {
        static void Main(string[] args)
        {
            int[] s = ReadLine().Split(' ').Select(int.Parse).ToArray();
            int R = s[0];
            int G = s[1];
            int B = s[2];
            int N = s[3];

            int ans = 0;int r = R; int g = G;
            for (int i = 0; i <= N / R; i++)
            {
                r = R * i;
                for (int j = 0; j <= N / G; j++)
                {
                    g = G * j;
                    if (0<= (N - (r + g)) && (N - (r + g)) % B == 0)
                    {
                        ans++;
                    }
                }
            }
            WriteLine(ans);
        }
    }
}