#include <stdio.h>
int main ()
{
int v ,t ,s ;
while (scanf ("%d%d",&v ,&t) == 2)
{
s = 2 * v *t ;
printf ("%d\n",s) ;
}
return 0 ;
}
int main ()
{
int v ,t ,s ;
while (scanf ("%d%d",&v ,&t) == 2)
{
s = 2 * v *t ;
printf ("%d\n",s) ;
}
return 0 ;
}