my %input= $cgi->Vars();

foreach $name (keys %input){
        $value = $input{$name};
       }

#now test for conditions
if ((-e $input{"whatever") && (-e $input{"wherever") )
  { 
    your subroutine goes here 
  }

# I may have missed some details involving autovification of hash keys, 
# and  grepping the %input hash keys may be better, but right now, 
# I'm not sure of the cleverest way to grep an array for 2 values.
# I leave that to you, or a more clever monk than me.