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>
# include <string.h>

void swap(int *nx, int *ny)
{
    int temp = *nx;
    *nx = *ny;
    *ny = temp;
}


void sort3(int *n1, int *n2, int *n3)
{
    if (*n1 > *n2) swap(n1, n2);
    if (*n2 > *n3) swap(n2, n3);
    if (*n1 > *n2) swap(n1, n2);
}


int main()
{
    int R, G, B, N;
    scanf("%d%d%d%d", &R, &G, &B, &N);
    sort3(&R, &G, &B);

    int r, g;
    int ans = 0;
    for (int i = 0; i < N/R + 1; ++i)
    {
        r = i;
        if (r*R > N) break;
        for (int j = 0; j < (N-r*R)/G + 1; ++j)
        {
            g = j;
            if (r*R + g*G > N) break;
            int rem = N - r*R - g*G;
            if (rem % B == 0) ans++;
        }
    }

    printf("%d\n", ans);

}