#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define ALL(v) v.begin(),v.end()
#define dbg(x) cerr << #x << ": " << (x) << endl;
template<class F, class S>
ostream& operator<<(ostream& os, pair<F,S>& p) {
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template<class Iter>
void print(Iter beg, Iter end) {
    for (Iter itr = beg; itr != end; ++itr) {
        cerr << *itr << ' ';
    }
    cerr << '\n';
}
ll t,a,b;

ll lcm(ll x, ll y) {
    return x / gcd(x,y) * y;
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    cin >> t >> a >> b;
    --t;

    ll ans = t / a + 1;
    ans += t / b + 1;
    ans -= t / lcm(a,b) + 1;
    cout << ans << '\n';
}