c全wa,求求各位大佬帮忙看看

#include <stdio.h>
#include <math.h>
double dis(double x1,double x2,double y1,double y2)
{
    double dis,s;
    s=pow((x2-x1),2)+pow((y2-y1),2);
    dis=sqrt(s);

    return dis;
}
int main()
{
    double a,b,c,d,s1,s2,c1;
    scanf("%lf%lf%lf%lf%lf%lf",&a,&b,&c,&d,&s1,&s2);
    c1=dis(a,b,c,d)+dis(a,b,s1,s2)+dis(c,d,s1,s2);
    printf("%.2lf",c1);
}