#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  while (a %= b ^= a ^= b ^= a)
    ;
  return b;
}
int lcm(int a, int b) { return (a * b) / gcd(a, b); }
long long power(long long a, long long b) {
  if (b == 0) {
    return 1;
  }
  if (b == 1) {
    return a;
  }
  if (b % 2 == 0) {
    return power(a * a, b / 2);
  } else {
    return (a * power(a * a, (b - 1) / 2));
  }
}
unsigned long long choose(unsigned long long n, unsigned long long k) {
  if (k > n) {
    return 0;
  }
  unsigned long long r = 1;
  for (unsigned long long d = 1; d <= k; ++d) {
    r *= n--;
    r /= d;
  }
  return r;
}
int main() {
  int x, y, a, b;
  cin >> x >> y >> a >> b;
  int d = lcm(x, y);
  cout << (b / d) - ((a - 1) / d) << endl;
  return 0;
}
