$mode = 'l';
$mode eq 'l' or $mode eq 'r' or die "\$mode must be \"l\" or \"r\".\n";
$input = "Frog Blast the Vent Core!";
if ($mode eq 'l')
{$input =~ tr {1234567890\-=`wertyuiop[]\\qsdfghjkl;'axcvbnm,./z}
{`1234567890\-=qwertyuiop[]\\asdfghjkl;'zxcvbnm,./};
$input =~ tr {!@#$%^&*()_+~WERTYUIOP\{\}|QSDFGHJKL:"AXCVBNM<>?Z}
{~!@#$%^&*()_+QWERTYUIOP\{\}|ASDFGHJKL:"ZXCVBNM<>?};}
else
{$input =~ tr {`1234567890\-=qwertyuiop[]\\asdfghjkl;'zxcvbnm,./}
{1234567890\-=`wertyuiop[]\\qsdfghjkl;'axcvbnm,./z};
$input =~ tr {~!@#$%^&*()_+QWERTYUIOP\{\}|ASDFGHJKL:"ZXCVBNM<>?}
{!@#$%^&*()_+~WERTYUIOP\{\}|QSDFGHJKL:"AXCVBNM<>?Z};}
print $input;