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

class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		BigInteger T = scanner.nextBigInteger(), A = scanner.nextBigInteger(), B = scanner.nextBigInteger();
		scanner.close();
		System.out.print(BigInteger.ONE.add(T.subtract(BigInteger.ONE).divide(A)).add(T.subtract(BigInteger.ONE).divide(B)).subtract(T.subtract(BigInteger.ONE).divide(A.multiply(B).divide(A.gcd(B)))));
	}
}