#!/usr/bin/perl
use strict;
use warnings;

my $N = $ARGV[0] || 0;
print nearest( $N );

sub nearest {
    my $N = shift;
    return $N if scalar(reverse $N) eq $N;

    my $pos = $N;
    ++$pos while scalar(reverse $pos) ne $pos;
    $pos = $pos - $N;

    my $neg = $N;
    --$neg while scalar(reverse $neg) ne $neg;
    $neg = $N - $neg;
    return $pos > $neg ? $N - $neg : $N + $pos;
}