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 DIVERTA2019B
{
    class Program
    {
        static void Main(string[] args)
        {
            var input = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToList();
            var output = 0;

            for (int i = 0; i < input[3] / input[0] + 1; i++)
            {
                for (int j = 0; j < input[3] / input[1] + 1; j++)
                {
                    var sum1 = input[0] * i + input[1] * j;

                    if (sum1 > input[3])
                    {
                        break;
                    }
                    else if (((input[3] - sum1) % input[2]) == 0)
                    {
                        // きっちり数があう
                        output++;
                    }
                }
            }

            Console.WriteLine(output);
        }
    }
}