//#define NDEBUG

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>

#include <list>
#include <set>
#include <map>
#include <vector>

using namespace std;

#undef max
#undef min
#define max(x,y) ((x)>(y)?(x):(y))
#define min(x,y) ((x)<(y)?(x):(y))

#ifdef NDEBUG
#define dprintf
#else
#define dprintf printf
#endif

int chomp(char *s)
{
	int len;
	
	len = strlen(s);
	while(len > 0 && (s[len-1] == '\r' || s[len-1] == '\n'))
		s[--len] = '\0';

	return len;
}


int cnt;
int depth_lim;
int seki_lim;

int gcd(int n, int m)
{
	int t;
	if (n < m) {
		t = n;
		n = m;
		m = t;
	}
	if (m == 0) return 0;
	while((t = n%m) != 0) {
		n = m;
		m = t;
	}
	return m;
}


void calc(int p,int q,int bunbo,int depth,int seki){
	int x,y,tmp;
	if(depth >= depth_lim){
		return;
	}
	if(seki >= seki_lim){
		return;
	}
	for( ; bunbo*seki <= seki_lim; bunbo++) {
		x = bunbo*p-q;
		y = bunbo*q;
		if(x == 0){
			cnt++;
			continue;
		}
		tmp = gcd(x,y);
		x /= tmp;
		y /= tmp;
		calc(x,y,bunbo,depth+1,bunbo*seki);
	}
}
int main()
{
	int q,p;
while(1){
	scanf("%d %d %d %d",&p,&q,&seki_lim,&depth_lim);
	if(p == 0 && q == 0 && seki_lim == 0 && depth_lim == 0) break;
	cnt=0;
	calc(p,q,1,0,1);
	printf("%d\n", cnt);
}
	return 0;
}