#include<math.h>
#include<stdio.h>
int main() {
	double a,x=M_PI,d=M_PI,r,eps=0.000001;
	scanf("%lf",&a);
	while (fabs(r=sin(x)-x/a) > eps) {
		printf("%f: %f\n", r, x);
		if (r < 0) { d /= 2; x -= d; } else x += d;
	}
	printf("%f: %f\n", r, x);
	return 0;
}