#include <stdio.h>
#include <math.h>
int main(void)
{
 cal_distance(int x1,int x2,int y1,int y2)

  int X,Y;
  double D,d;

  X = x2 - x1;
  Y = y1 - y2;

  D = (X*X)(Y*Y);

  d = sprt(D);
  
  return (d);
}

int main(void)
{

 int  x1, x2, y1, y2;
 
 scanf("%d %d %d %d",x1, x2, y1, y2);
 
 distance = cal_distance(int x1,int x2,int y1,int y2);
 
 printf("%d"distance);

 return 0;

}