#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<queue>
#include<vector>
#include <bitset>
#include<math.h>
using namespace std;
#define INF 11000000000
#define MOD 1000000007
typedef long long ll;
typedef pair<ll,ll> P;

//計算量はO(log max(a,b))
ll lcm(ll x,ll y){
  ll mindata,maxdata;
  mindata=min(x,y);
  maxdata=max(x,y);
  while(maxdata%mindata!=0){
    ll temp;
    temp=maxdata%mindata;
    maxdata=mindata;
    mindata=temp;
  }
  return x*(y/mindata);
}

int main(){
    ll T,A,B,a;
    cin>>T>>A>>B;
    a=lcm(A,B);
    ll ans=(T-1)/A+(T-1)/B+1-(T-1)/a;
    cout<<ans<<endl;
}