杭电2001

#include <stdio.h>#include <math.h>int main (void){    double a,b,c,d;    while(scanf("%lf%lf%lf%lf",&a,&b,&c,&d)!=EOF)    {        printf("%.2lf\n",sqrt(pow(a-c,2)+pow(b-d,2)));    }    return 0;}