Interfacing PushButton

I want to sense when a port pin goes high.
I have connected it to Vcc through a resitor
and pushbutton , so when pushbutton is pressed
the port pin goes high .But to configure port
for input I must first write 0xFF to Port .

     V
     |       R1       PB     |
     |_____/\/\/\____.--.____|Port Pin
                             |