杭电2001.为什么是wrong answer?

杭电2001.为什么是wrong answer?
#include
#include
main()
{
float x1,x2,y1,y2;
while(scanf("%f %f %f %f",&x1,&x2,&y1,&y2)!=EOF)
{
printf("%.2f",sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)));
putchar('\n');
}
}