#include<stdio.h>
#include<math.h>
int dis(int x1,int y1,int x2,int y2)
{
    float s;
    s=sqrt(1.0*abs(x2-x1)*abs(x2-x1)+1.0*abs(y2-y1)*abs(y2-y1));
    return s;
}
int main()
{
    int x1,y1,x2,y2,x3,y3;
    scanf("%d %d",&x1,&y1);
    scanf("%d %d",&x2,&y2);
    scanf("%d %d",&x3,&y3);
    float s;
    s=dis(x1,y1,x2,y2)+dis(x3,y3,x2,y2)+dis(x3,y3,x1,y1);
    printf("%.2f",s);
    return 0;
}

明明样例都能输出来，，