my( @items )= <FILE>;
pop @items;       # Remove the "offset"
chomp @items;
my %value;
@value{ @items }= 1 .. @items;
$_ += rand(@items/3) for @value{ keys %value };
@items= sort { $value{$a} <=> $value{$b} } @items;
print NEWFILE join "\n", @items, 0, '';
# move NEWFILE to replace FILE