求距离

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