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 Ruby (2.3.3) (judge verdict: Accepted)

input=gets.chomp.split()
a=input[0].to_i
b=input[1].to_i
c=input[2].to_i
n=input[3].to_i

count=0
sum=0

i = n / c

while i >= 0
  j = (n - (c * i)) / b
  while j >= 0
    k = (n - (c * i) - (b * j)) / a
    sum = (c * i) + (b * j) + (a * k)
    if sum == n
      count += 1
    end
    j -= 1
  end
  i -= 1
end

puts count