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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"fmt"
)

func main() {
	var R, G, B, N int
	fmt.Scan(&R, &G, &B, &N)
	ans := 0
	//start := time.Now()
	for r := 0; r*R <= N; r++ {
		rr := r * R
		for g := 0; g*G <= N-rr; g++ {
			gg := g * G
			b := (N - rr - gg) / B
			if b >= 0 && (N-rr-gg)%B == 0 {
				ans++
			}
		}
	}
	//elapsed := time.Now().Sub(start)
	//fmt.Println(ans, elapsed)
	fmt.Println(ans)
}