#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
using namespace std;

// #{split of  p/q}
int solve( int p, int q, int a, int n, int d, int cp, int cq )
{
  int sum = 0;
  do
    {
      // cp/cq + 1/d
      int cp2 = cp*d + cq;
      int cq2 = cq*d;
      if( cq2 > a )
	break;

      //cout << string(3-n,' ') << d;

      if( cp2 * q == cq2 * p )
	{
	  //cout << "*" << endl;
	  ++sum;
	}
      else
	{
	  //cout << endl;
	  if( n != 1 )
	    sum += solve( p, q, a, n-1, d, cp2, cq2 );
	}
      ++d;
    }
  while( 1 );
  return sum;
}

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