#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
 
    long long N,A,B; cin >> N >> A >> B;
    long long answer = N;
    answer -= N/A+N/B;
    answer += N/(A*B/gcd(A,B));
    cout << answer << endl;
}