#include <stdio.h>
#include <math.h>
int main(int argc, char *argv[])
{float x,y;
scanf("%f",&x);
if(x>6)
y=5*(x*x+4*x-6)/27.0;
else if(0<x&&x<=6)
y=log(16)/log(3)+x;
else
y=23*abs(x*x*x+4)/7.0;
printf("%.3f",y);
return 0;
}