#include <iostream>

int Solve(int depth,int shi,int bo,int prev,int p,int q,int a,int n)
{
    int ans = 0;
    if(p*bo == shi*q)return 1;
    if(p*bo < shi*q || depth == n)return 0;
    for(int i = prev ; bo*i <= a ; i++)
	ans += Solve(depth+1,shi*i+bo,bo*i,i,p,q,a,n);
    return ans;
}

int main()
{
    int p,q,a,n;
    while(cin >> p >> q >> a >> n , p && q && a && n)
	cout << Solve(0,0,1,1,p,q,a,n) << endl;
    return 0;
}