杭电oj 计算两点间的距离

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main()
{
    double x1,x2,y1,y2,dis;
    while(scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2)!=EOF)
    {
        dis = sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
        printf("%.2lf\n",dis);
    }
    return 0;

}