#include <stdio.h>
int main() {
    int x1,x2,y1,y2;
    scanf("%d %d",&x1,&y1);
    scanf("%d %d",&x2,&y2);
    float l=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
    int k=l;
    printf("%d",k);
    return 0;
}