import java.math.BigInteger;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger a = BigInteger.valueOf(sc.nextLong());
        BigInteger b = BigInteger.valueOf(sc.nextLong());
        BigInteger c = BigInteger.valueOf(sc.nextLong());
        BigInteger d = BigInteger.valueOf(sc.nextLong());
        BigInteger mul = a.multiply(c);
        if (mul.compareTo(a.multiply(d)) < 0)
            mul = a.multiply(d);
        if (mul.compareTo(b.multiply(c)) < 0)
            mul = b.multiply(c);
        if (mul.compareTo(b.multiply(d)) < 0)
            mul = b.multiply(d);

        System.out.println(mul);
    }
} import java.math.BigInteger; BigInteger java.math import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger a = BigInteger.valueOf(sc.nextLong());
        BigInteger b = BigInteger.valueOf(sc.nextLong());
        BigInteger c = BigInteger.valueOf(sc.nextLong());
        BigInteger d = BigInteger.valueOf(sc.nextLong());
        BigInteger mul = a.multiply(c);
        if (mul.compareTo(a.multiply(d)) < 0)
            mul = a.multiply(d);
        if (mul.compareTo(b.multiply(c)) < 0)
            mul = b.multiply(c);
        if (mul.compareTo(b.multiply(d)) < 0)
            mul = b.multiply(d);

        System.out.println(mul);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger a = BigInteger.valueOf(sc.nextLong());
        BigInteger b = BigInteger.valueOf(sc.nextLong());
        BigInteger c = BigInteger.valueOf(sc.nextLong());
        BigInteger d = BigInteger.valueOf(sc.nextLong());
        BigInteger mul = a.multiply(c);
        if (mul.compareTo(a.multiply(d)) < 0)
            mul = a.multiply(d);
        if (mul.compareTo(b.multiply(c)) < 0)
            mul = b.multiply(c);
        if (mul.compareTo(b.multiply(d)) < 0)
            mul = b.multiply(d);

        System.out.println(mul);
    } main {
        Scanner sc = new Scanner(System.in);
        BigInteger a = BigInteger.valueOf(sc.nextLong());
        BigInteger b = BigInteger.valueOf(sc.nextLong());
        BigInteger c = BigInteger.valueOf(sc.nextLong());
        BigInteger d = BigInteger.valueOf(sc.nextLong());
        BigInteger mul = a.multiply(c);
        if (mul.compareTo(a.multiply(d)) < 0)
            mul = a.multiply(d);
        if (mul.compareTo(b.multiply(c)) < 0)
            mul = b.multiply(c);
        if (mul.compareTo(b.multiply(d)) < 0)
            mul = b.multiply(d);

        System.out.println(mul);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) BigInteger a = BigInteger.valueOf(sc.nextLong()); a BigInteger.valueOf(sc.nextLong()) BigInteger.valueOf BigInteger sc.nextLong() sc.nextLong sc BigInteger b = BigInteger.valueOf(sc.nextLong()); b BigInteger.valueOf(sc.nextLong()) BigInteger.valueOf BigInteger sc.nextLong() sc.nextLong sc BigInteger c = BigInteger.valueOf(sc.nextLong()); c BigInteger.valueOf(sc.nextLong()) BigInteger.valueOf BigInteger sc.nextLong() sc.nextLong sc BigInteger d = BigInteger.valueOf(sc.nextLong()); d BigInteger.valueOf(sc.nextLong()) BigInteger.valueOf BigInteger sc.nextLong() sc.nextLong sc BigInteger mul = a.multiply(c); mul a.multiply(c) a.multiply a c if (mul.compareTo(a.multiply(d)) < 0)
            mul = a.multiply(d); mul.compareTo(a.multiply(d)) < 0 mul.compareTo(a.multiply(d)) mul.compareTo mul a.multiply(d) a.multiply a d 0 mul = a.multiply(d) mul a.multiply(d) a.multiply a d if (mul.compareTo(b.multiply(c)) < 0)
            mul = b.multiply(c); mul.compareTo(b.multiply(c)) < 0 mul.compareTo(b.multiply(c)) mul.compareTo mul b.multiply(c) b.multiply b c 0 mul = b.multiply(c) mul b.multiply(c) b.multiply b c if (mul.compareTo(b.multiply(d)) < 0)
            mul = b.multiply(d); mul.compareTo(b.multiply(d)) < 0 mul.compareTo(b.multiply(d)) mul.compareTo mul b.multiply(d) b.multiply b d 0 mul = b.multiply(d) mul b.multiply(d) b.multiply b d System.out.println(mul) System.out.println System.out System System.out mul String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger a = BigInteger.valueOf(sc.nextLong());
        BigInteger b = BigInteger.valueOf(sc.nextLong());
        BigInteger c = BigInteger.valueOf(sc.nextLong());
        BigInteger d = BigInteger.valueOf(sc.nextLong());
        BigInteger mul = a.multiply(c);
        if (mul.compareTo(a.multiply(d)) < 0)
            mul = a.multiply(d);
        if (mul.compareTo(b.multiply(c)) < 0)
            mul = b.multiply(c);
        if (mul.compareTo(b.multiply(d)) < 0)
            mul = b.multiply(d);

        System.out.println(mul);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger a = BigInteger.valueOf(sc.nextLong());
        BigInteger b = BigInteger.valueOf(sc.nextLong());
        BigInteger c = BigInteger.valueOf(sc.nextLong());
        BigInteger d = BigInteger.valueOf(sc.nextLong());
        BigInteger mul = a.multiply(c);
        if (mul.compareTo(a.multiply(d)) < 0)
            mul = a.multiply(d);
        if (mul.compareTo(b.multiply(c)) < 0)
            mul = b.multiply(c);
        if (mul.compareTo(b.multiply(d)) < 0)
            mul = b.multiply(d);

        System.out.println(mul);
    }
} Main
import java.math.BigInteger;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger a = BigInteger.valueOf(sc.nextLong());
        BigInteger b = BigInteger.valueOf(sc.nextLong());
        BigInteger c = BigInteger.valueOf(sc.nextLong());
        BigInteger d = BigInteger.valueOf(sc.nextLong());
        BigInteger mul = a.multiply(c);
        if (mul.compareTo(a.multiply(d)) < 0)
            mul = a.multiply(d);
        if (mul.compareTo(b.multiply(c)) < 0)
            mul = b.multiply(c);
        if (mul.compareTo(b.multiply(d)) < 0)
            mul = b.multiply(d);

        System.out.println(mul);
    }
}