#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
#define DUMP(x)  cout << #x << " = " << (x) << endl;
#define FOR(i, m, n) for(ll i = m; i < n; i++)
#define IFOR(i, m, n) for(ll i = n - 1; i >= m; i-- )
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
#define FOREACH(x,a) for(auto& (x) : (a) )
#define ALL(v) (v).begin(), (v).end()
#define SZ(x) ll(x.size())

ll gcd (ll a, ll b){
  if(b == 0) return a;
  return gcd(b, a%b);
}

ll lcm(ll a, ll b){
  return a / gcd(a,b) * b;
}

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