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.Linq;

namespace diverta2019_b
{
    class Program
    {
        static void Main(string[] args)
        {
            var RGBN = (Console.ReadLine().Split(' ').Select(x => int.Parse(x))).ToList();
            var R = RGBN[0];
            var G = RGBN[1];
            var B = RGBN[2];
            var N = RGBN[3];
            var r = 0;

            for (int i = 0; i <= N; i += R)
            {
                for (int j = 0; j <= N; j += G)
                {
                    if (i + j > N) break;

                    //残りがBで割り切れる
                    if ((N - (i + j)) % B == 0) r++;
                }
            }

            Console.WriteLine(r);

        }
    }
}