哪里错了

#include<stdio.h>
#include<math.h>
double dis(double x1,double x2,double y1,double y2);
int main()
{
	double x1,x2,x3,y1,y2,y3,ab,ac,bc,s;
	scanf("%lf %lf %lf %lf %lf %lf",&x1,&y1,&x2,&y2,&x3,&y3);
	ab=dis(x1,y1,x2,y2);
    ac=dis(x1,y1,x3,y3);
    bc=dis(x2,y2,x3,y3);
    s=ab+ac+bc;
    printf("%.2lf",s);
    return 0;
}
double dis(double x1,double x2,double y1,double y2)
{
	double s;
	s=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
	s=sqrt(s);
	return s;
}