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;

namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            var ss = Console.ReadLine().Split();
            var R = int.Parse(ss[0]);
            var G = int.Parse(ss[1]);
            var B = int.Parse(ss[2]);
            var N = int.Parse(ss[3]);

            var count = 0;
            for (int r = 0; true; r++)
            {
                var sumR = R * r;
                if (sumR > N) break;
                for (int g = 0; true; g++)
                {
                    var sumRG = sumR + G * g;
                    if (sumRG > N) break;

                    if ((N - sumRG) % B == 0) count++;
                }
            }

            Console.WriteLine(count);
        }
    }
}