import java.math.BigInteger;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		new Main().run();
	}

	public void run() {
		Scanner sc = new Scanner(System.in);
		BigInteger T = new BigInteger(sc.next()).subtract(BigInteger.ONE);
		BigInteger A = new BigInteger(sc.next());
		BigInteger B = new BigInteger(sc.next());
		BigInteger ans = BigInteger.ZERO;
		ans = ans.add(T.divide(A));
		ans = ans.add(T.divide(B));
		ans = ans.subtract(T.divide(A.multiply(B).divide(A.gcd(B))));
		ans = ans.add(BigInteger.ONE);
		System.out.println(ans);
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}