#include <stdio.h>

int main() {
    int x1,y1,x2,y2;
    scanf("%d %d\n",&x1,&y1);
    scanf("%d %d\n",&x2,&y2);
    int d1=x1-x2;
    int d2=y1-y2;
    printf("%d",d1*d1+d2*d2);
    return 0;
}