#include <iostream>
#include <numeric>

using lint = long long;

void solve() {
    lint t, a, b;
    std::cin >> t >> a >> b;

    std::cout << (t - 1) / a + (t - 1) / b - (t - 1) / a / (b / std::gcd(a, b)) + 1
              << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}