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>
#include<vector>
#include<string>
#include<utility>
#include<algorithm>
#include<stack>
#include<queue>

using namespace std;

typedef pair<int, int> P;

int R, G, B, N;

int main() {
	cin >> R >> G >> B >> N;
	int ans = 0;
	int k;
	for (int i = 0; i <= N / R; i++) {
		for (int j = 0; j <= N / G; j++) {
			k = N - (R * i + G * j);
			if (k >= 0 && k % B == 0) { ans++; }
		}
	}

	cout << ans << endl;
}