#! perl -slw
use strict;

my $n = <>;
my %counts;
++$counts{ $_ } for split ' ', do{ local $/, <> };
my @sorted = sort{ $counts{$b} <=> $counts{$a} }keys %counts;

my( $i, $min, $total ) = (0) x 3;
++$min while ( $total += $counts{ $sorted[ $i++ ] } ) < $n;
print $min+1;
print for @sorted[ 0 .. $min ];