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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
using namespace std;

int main(){
    int R, G, B, N;
    cin >> R >> G >> B >> N;
    int ans = 0;
    
    for(int r = 0; r * R <= N; r++){
        for(int g = 0; g * G <= N; g++){
            if((N - (r * R) - (g * G)) >= 0){
                if((N - (r * R) - (g * G)) % B == 0){
                    ans++;
                }
            }
        }
    }
    
    cout << ans << endl;

    return 0;
}