#include <stdio.h>
#include <math.h>

struct Coordinate{
double x;
double y;
double z;
};

int main(void)
{
struct Coordinate a={1,5,2};
struct Coordinate b={5,3,1};
struct Coordinate c={2,8,4};

double length_ab;
double length_co;

length_ab=sqrt((b.x-a.x)*(b.x-a.x)+(b.y-a.y)*(b.y-a.y)+(b.z-a.z)*(b.z-a.z));
length_co=sqrt(c.x*c.x+c.y*c.y+c.z*c.z);

if(length_ab>length_co){
printf("length ab :%lf\n",length_ab);
}
else{
printf("length co :%lf\n",length_co);
}
	return 0;
}