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 (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#define swap(type, x, y)  do{ type t = x; x = y; y = t; }while(0)

int main(){
  long a[4] = {0}, n;
  for(int i=1; i<=3; i++)  scanf("%ld", a+i);
  scanf("%ld", &n);
  
  for(int i=1; i<3; i++)
    for(int j=i+1; j<=3; j++)
      if(a[i] < a[j])
	swap(long, a[i], a[j]);
  long ans = 0;
  for(long i=0; i<=n/a[1]; i++){
    for(long j=0; j<=(n-a[1]*i)/a[2]; j++){
      if((n-a[1]*i-a[2]*j) % a[3] == 0)
	ans++;
    }
  }
  printf("%ld\n", ans);
  return 0;
}