#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 long long ll;
typedef long double ld;
typedef pair<int,int> P;
ll gcd(ll a, ll b){
    if(b == 0)return a;
    return gcd(b,a%b);
}

ll lcm(ll c, ll d){
    ll g = gcd(c,d);
    ll l = c/g*d;//最小公倍数
    return l;
}
int main() {
  ll t, a, b;
  cin >> t >> a >> b;
  t--;
  cout << (t / a) + (t / b) - (t / lcm(a, b)) + 1 << endl;
  return 0;
}