B - 计算两点间的距离

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