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;

namespace AtcoderProgram
{
    class Program
    {
        static void Main(string[] args)
        {
            var line = Console.ReadLine().Split(' ');
            var r = int.Parse(line[0]);
            var g = int.Parse(line[1]);
            var b = int.Parse(line[2]);
            var n = int.Parse(line[3]);

            var conb = 0;

            for(int i=0; i *b <n+1; i++)
            {
                conb += pair(r, g, n - b * i);
              
            }

            Console.WriteLine(conb);

        }

        static int pair(int r, int g, int n)
        {
            int conb = 0;
            for(int i=0; i*r< n+1; i++)
            {
                if ((n - r * i) % g == 0 ) {
                    conb++;
                } 
            }
            return conb;
        }
    }

}