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 PyPy3 (7.3.0) (judge verdict: Accepted)

# https://atcoder.jp/contests/diverta2019/tasks/diverta2019_b
R, G, B, N = map(int, input().split())

# rR+gG+bB=Nになるようなrgbの組み合わせの個数
# N<3000なのでO(n**2)で全探索して良さそう
# r,gがgivenのとき、rR+gG-N=-bB が成り立つ整数bが存在すれば、良い
ans = 0
for r in range(0, N + 1):
    for g in range(0, N + 1):
        left = (N - (r * R + g * G))
        if left >= 0 and left % B == 0:
            ans += 1
print(ans)