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.Text;
using System.Threading.Tasks;

namespace A
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] str = Console.ReadLine().Split(' ');
            List<int> ks = new List<int>();
            for (int i = 0; i < 3; i++)
            {
                ks.Add(int.Parse(str[i]));
            }
            ks.Sort((a, b) => b - a);
            int n = int.Parse(str[3]);
            int count = 0;
            int Amax = n / ks[0];
            for (int i = 0; i <= Amax; i++)
            {
                for (int k = 0; k <= n-i*ks[0]; k++)
                { int l = n - i * ks[0] - k * ks[1];
                    if (l>=0&&l%ks[2]==0)
                    {
                        count++; }
                }
            }
            Console.WriteLine(count);
            
        }
    }
}