#!/usr/bin/perl

$line = "I'z abg fnlvat lbh nfxrq n ubzrjbex dhrfgvba...";

for ($i = 0; $i < length $line ; $i++) {
   $char = substr $line, $i, 1;
   if ($char eq "a") {
      $char = "n";
   } elsif ($char eq "b") {
      $char = "o";
   } elsif ($char eq "c") {
      $char = "p";
   } elsif ($char eq "d") {
      $char = "q";
   } elsif ($char eq "e") {
      $char = "r";
   } elsif ($char eq "f") {
      $char = "s";
   } elsif ($char eq "g") {
      $char = "t";
   } elsif ($char eq "h") {
      $char = "u";
   } elsif ($char eq "i") {
      $char = "v";
   } elsif ($char eq "j") {
      $char = "w";
   } elsif ($char eq "k") {
      $char = "x";
   } elsif ($char eq "l") {
      $char = "y";
   } elsif ($char eq "m") {
      $char = "z";
   } elsif ($char eq "n") {
      $char = "a";
   } elsif ($char eq "o") {
      $char = "b";
   } elsif ($char eq "p") {
      $char = "c";
   } elsif ($char eq "q") {
      $char = "d";
   } elsif ($char eq "r") {
      $char = "e";
   } elsif ($char eq "s") {
      $char = "f";
   } elsif ($char eq "t") {
      $char = "g";
   } elsif ($char eq "u") {
      $char = "h";
   } elsif ($char eq "v") {
      $char = "i";
   } elsif ($char eq "w") {
      $char = "j";
   } elsif ($char eq "x") {
      $char = "k";
   } elsif ($char eq "y") {
      $char = "l";
   } elsif ($char eq "z") {
      $char = "m";
   }
   $decoded .= $char;
}

print $decoded, "\n";