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 <bits/stdc++.h>
using namespace std;

using LL = long long;

#define ALL(a) begin((a)), end((a))
#define FOR(i, a, b) for (int(i) = (a); (i) < (b); (i)++)
#define RFOR(i, a, b) for (int(i) = (a); (i) > (b); (i)--)
#define debug(x) cout << #x << " : " << x << '\n'

const int INF = 1e9;

int main() {
  int ans = 0;
  int R, G, B, N;
  // cin >> R >> G >> B >> N;
  scanf("%d %d %d %d", &R, &G, &B, &N);

  FOR(i, 0, N + 1) {
    FOR(j, 0, N + 1) {
      int temp = N - (R * i + G * j);

      if (temp < 0) {
        continue;
      }

      if ((temp % B) == 0) {
        ans++;
      }
    }
  }

  printf("%d\n", ans);

  return 0;
}