import std;

void main() {
    long T, A, B;
    readf("%d %d %d\n", T, A, B);

    long C = A / gcd(A, B) * B;

    long res = (T + A - 1) / A + (T + B - 1) / B - (T + C - 1) / C;
    res.writeln;
}