// question of uri 1015 | Distance Between Two Points |
#include <stdio.h>
int main()
{
float x1,x2,y1,y2,a;
scanf("%f %f %f %f",&x1,&y1,&x2,&y2);
a=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
printf("%.4f\n",a);
return 0;
}
// question of uri 1015 | Distance Between Two Points |