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;
public class ABC125B {
    public static void Main() {
        int R, G, B, N, ans = 0;
        int rMax, gMax, bMax;
        string[] str = System.Console.ReadLine().Split(' ');
        R = int.Parse(str[0]);
        G = int.Parse(str[1]);
        B = int.Parse(str[2]);
        N = int.Parse(str[3]);

        rMax = N / R;
        for(int r = 0; r <= rMax; r++) {
            gMax = (N - R * r) / G;
            for(int g = 0; g <= gMax; g++) {
                if ((N - R * r - G * g) % B == 0)  {
                    ans++;
                }
            }
        }
        System.Console.WriteLine(ans);
    }
}