#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
int main() {
  long long x, y, a, b, g, num, lcm;
  cin >> x >> y >> a >> b;
  g = gcd(x, y);
  lcm = y / g;
  lcm *= x;
  num = b / lcm - (a - 1) / lcm;
  cout << num;
  return 0;
}
