import java.math.BigDecimal;
import java.util.Scanner;
 
public class Main {
	public static void main(String[] args){
 
		Scanner sc = new Scanner(System.in);
 
		// 整数の入力
		BigDecimal a = sc.nextBigDecimal();
		BigDecimal b = sc.nextBigDecimal();
		BigDecimal c = sc.nextBigDecimal();
		BigDecimal d = sc.nextBigDecimal();
		
		BigDecimal e = a.multiply(c);
 
		if (e.compareTo(a.multiply(d)) < 0) {
			e = a.multiply(d);
		}
		if (e.compareTo(b.multiply(c)) < 0) {
			e = b.multiply(c);
		}
		if (e.compareTo(b.multiply(d)) < 0) {
			e = b.multiply(d);
		}
      System.out.println(e);
	}
} import java.math.BigDecimal; BigDecimal java.math import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args){
 
		Scanner sc = new Scanner(System.in);
 
		// 整数の入力
		BigDecimal a = sc.nextBigDecimal();
		BigDecimal b = sc.nextBigDecimal();
		BigDecimal c = sc.nextBigDecimal();
		BigDecimal d = sc.nextBigDecimal();
		
		BigDecimal e = a.multiply(c);
 
		if (e.compareTo(a.multiply(d)) < 0) {
			e = a.multiply(d);
		}
		if (e.compareTo(b.multiply(c)) < 0) {
			e = b.multiply(c);
		}
		if (e.compareTo(b.multiply(d)) < 0) {
			e = b.multiply(d);
		}
      System.out.println(e);
	}
} Main public static void main(String[] args){
 
		Scanner sc = new Scanner(System.in);
 
		// 整数の入力
		BigDecimal a = sc.nextBigDecimal();
		BigDecimal b = sc.nextBigDecimal();
		BigDecimal c = sc.nextBigDecimal();
		BigDecimal d = sc.nextBigDecimal();
		
		BigDecimal e = a.multiply(c);
 
		if (e.compareTo(a.multiply(d)) < 0) {
			e = a.multiply(d);
		}
		if (e.compareTo(b.multiply(c)) < 0) {
			e = b.multiply(c);
		}
		if (e.compareTo(b.multiply(d)) < 0) {
			e = b.multiply(d);
		}
      System.out.println(e);
	} main {
 
		Scanner sc = new Scanner(System.in);
 
		// 整数の入力
		BigDecimal a = sc.nextBigDecimal();
		BigDecimal b = sc.nextBigDecimal();
		BigDecimal c = sc.nextBigDecimal();
		BigDecimal d = sc.nextBigDecimal();
		
		BigDecimal e = a.multiply(c);
 
		if (e.compareTo(a.multiply(d)) < 0) {
			e = a.multiply(d);
		}
		if (e.compareTo(b.multiply(c)) < 0) {
			e = b.multiply(c);
		}
		if (e.compareTo(b.multiply(d)) < 0) {
			e = b.multiply(d);
		}
      System.out.println(e);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) BigDecimal a = sc.nextBigDecimal(); a sc.nextBigDecimal() sc.nextBigDecimal sc BigDecimal b = sc.nextBigDecimal(); b sc.nextBigDecimal() sc.nextBigDecimal sc BigDecimal c = sc.nextBigDecimal(); c sc.nextBigDecimal() sc.nextBigDecimal sc BigDecimal d = sc.nextBigDecimal(); d sc.nextBigDecimal() sc.nextBigDecimal sc BigDecimal e = a.multiply(c); e a.multiply(c) a.multiply a c if (e.compareTo(a.multiply(d)) < 0) {
			e = a.multiply(d);
		} e.compareTo(a.multiply(d)) < 0 e.compareTo(a.multiply(d)) e.compareTo e a.multiply(d) a.multiply a d 0 {
			e = a.multiply(d);
		} e = a.multiply(d) e a.multiply(d) a.multiply a d if (e.compareTo(b.multiply(c)) < 0) {
			e = b.multiply(c);
		} e.compareTo(b.multiply(c)) < 0 e.compareTo(b.multiply(c)) e.compareTo e b.multiply(c) b.multiply b c 0 {
			e = b.multiply(c);
		} e = b.multiply(c) e b.multiply(c) b.multiply b c if (e.compareTo(b.multiply(d)) < 0) {
			e = b.multiply(d);
		} e.compareTo(b.multiply(d)) < 0 e.compareTo(b.multiply(d)) e.compareTo e b.multiply(d) b.multiply b d 0 {
			e = b.multiply(d);
		} e = b.multiply(d) e b.multiply(d) b.multiply b d System.out.println(e) System.out.println System.out System System.out e String[] args args public class Main {
	public static void main(String[] args){
 
		Scanner sc = new Scanner(System.in);
 
		// 整数の入力
		BigDecimal a = sc.nextBigDecimal();
		BigDecimal b = sc.nextBigDecimal();
		BigDecimal c = sc.nextBigDecimal();
		BigDecimal d = sc.nextBigDecimal();
		
		BigDecimal e = a.multiply(c);
 
		if (e.compareTo(a.multiply(d)) < 0) {
			e = a.multiply(d);
		}
		if (e.compareTo(b.multiply(c)) < 0) {
			e = b.multiply(c);
		}
		if (e.compareTo(b.multiply(d)) < 0) {
			e = b.multiply(d);
		}
      System.out.println(e);
	}
} public class Main {
	public static void main(String[] args){
 
		Scanner sc = new Scanner(System.in);
 
		// 整数の入力
		BigDecimal a = sc.nextBigDecimal();
		BigDecimal b = sc.nextBigDecimal();
		BigDecimal c = sc.nextBigDecimal();
		BigDecimal d = sc.nextBigDecimal();
		
		BigDecimal e = a.multiply(c);
 
		if (e.compareTo(a.multiply(d)) < 0) {
			e = a.multiply(d);
		}
		if (e.compareTo(b.multiply(c)) < 0) {
			e = b.multiply(c);
		}
		if (e.compareTo(b.multiply(d)) < 0) {
			e = b.multiply(d);
		}
      System.out.println(e);
	}
} Main
import java.math.BigDecimal;
import java.util.Scanner;
 
public class Main {
	public static void main(String[] args){
 
		Scanner sc = new Scanner(System.in);
 
		// 整数の入力
		BigDecimal a = sc.nextBigDecimal();
		BigDecimal b = sc.nextBigDecimal();
		BigDecimal c = sc.nextBigDecimal();
		BigDecimal d = sc.nextBigDecimal();
		
		BigDecimal e = a.multiply(c);
 
		if (e.compareTo(a.multiply(d)) < 0) {
			e = a.multiply(d);
		}
		if (e.compareTo(b.multiply(c)) < 0) {
			e = b.multiply(c);
		}
		if (e.compareTo(b.multiply(d)) < 0) {
			e = b.multiply(d);
		}
      System.out.println(e);
	}
}