import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigInteger;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] sa = br.readLine().split(" ");
		BigInteger t = new BigInteger(sa[0]).subtract(BigInteger.ONE);
		BigInteger a = new BigInteger(sa[1]);
		BigInteger b = new BigInteger(sa[2]);
		br.close();

		BigInteger x = t.divide(a).add(BigInteger.ONE);
		BigInteger y = t.divide(b).add(BigInteger.ONE);
		BigInteger z = a.multiply(b).divide(a.gcd(b));
		BigInteger w = t.divide(z).add(BigInteger.ONE);
		System.out.println(x.add(y).subtract(w).toString());
	}
}