#include <stdio.h>
#include <math.h>
 
struct Coordinate{
	double x;
	double y;
	double z;
}a = { 1, 5, 2 }, b = { 5, 3, 1 }, c = { 2, 8, 4 };
int main(void)
{
	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;
}
 

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