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)

inputs = STDIN.gets.chomp.split(' ').map(&:to_i)

R = inputs[0]
G = inputs[1]
B = inputs[2]
N = inputs[3]

count = 0

n_r = N / R
n_g = N / G
n_b = N / B

(0..n_r).each do |r|
  rr = R * r

  if rr == N
    count += 1
    next
  end

  (0..n_g).each do |g|
    gg = G * g

    next if (rr+gg) > N

    if (rr + gg) == N
      count += 1
      next
    end

    rg = rr + gg

    count += 1 if (N - rg) % B == 0
  end
end

puts count