Using hexadecimal with gp

["giovanniparodi79@yahoo.it" <giovanniparodi79@yahoo.it>]

Hello everybody,
I'm trying to use the GP calculator in order to evaluate the expression
X^N mod N

I'm able to evaluate this expression, however I would like to use, as 
input to the Mod( ) number expressed in hexadecimal notation.
However I tried
Mod(0x77, 0x11),
Mod(77h, 11h)
but none of this notation is accepted.
I searched for hex on the pdf file provided as help with pari, but I 
wasn't able to find reference to this aspect.
Any help will be appreciated.