import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int[][] arr = new int[2][2];
for(int i = 0; i < arr.length; i++) {
for(int j = 0; j < arr[i].length; j++) {
arr[i][j] = scan.nextInt();
}
}
int d = (int)(Math.pow(arr[0][0] - arr[1][0], 2) + Math.pow(arr[0][1] - arr[1][1], 2));
System.out.println(d);
}
}