#include <stdio.h>
int main ()
{
int n ;
while (scanf ("%d",&n) == 1 && n !=0)
{
n = n + n/2 ;
printf ("%d\n",n) ;
}
return 0 ;
}
int main ()
{
int n ;
while (scanf ("%d",&n) == 1 && n !=0)
{
n = n + n/2 ;
printf ("%d\n",n) ;
}
return 0 ;
}