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

double enshu(double r)
{
	return 2 * M_PI * r;
}

double menseki(double &r)
{
	return M_PI * r * r;
}

int main()
{
	double	r, ring, area;

	printf("半径rを入力：\n");
	scanf("%lf", &r);
	ring = enshu(r);
	area = menseki(r);
	printf("円周：%f\n", ring);
	printf("面積：%f\n", area);
	return 0;
}