#include <bits/stdc++.h>
using namespace std;

long long gcd(long long a, long long b) {
  if (b == 0) {
    return a;
  }
  return gcd(b, a % b);
}
int main() {
  long long t, a, b;
  cin>>t>>a>>b;
  long long g = gcd(a, b);
  long long l = a * b / g;

  cout<<(t-1)/a + (t-1)/b - (t-1)/l + 1<<endl;
}