#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef unsigned long long ll;
typedef long double ld;
typedef pair<int,int> P;

int main() {
  ll t,a,b;cin>>t>>a>>b;t--;
  ll l=a/gcd(a,b)*b;
  ll ans=t/a+t/b-t/l+1;
  cout<<ans<<endl;
  return 0;
}