#!/usr/bin/perl 
use strict;

sub fib {
  my $n = shift;
  return 1 if $n eq 1 || $n eq 2;
  fib($n-1) + fib($n-2);
}

while (42) {
  print "n = ";
  my $n = <>; chomp($n);
  last unless $n;
  print "fib($n) = ", fib($n),"\n";
}