# From http://rosettacode.org/wiki/Longest_common_subsequence#Perl_6
# Be advised: I was not the original author of this code; I adapted and
# refactored it to match the way I would have written it, but it may count
# as plagiarism to you.

sub lcs ( Str $xstr, Str $ystr ) {
    my @xs = $xstr.comb;
    my @ys = $ystr.comb;

    my @lengths = map { [ 0 xx (1+@ys) ] }, ^(1+@xs);

    for @xs.keys X @ys.keys -> $i, $j {
        @lengths[$i+1][$j+1] = @xs[$i] eq @ys[$j]
            ??   @lengths[$i][$j]+1
            !! ( @lengths[$i][$j+1], @lengths[$i+1][$j] ).max;
    }

    my ( $x, $y ) = ( +@xs, +@ys );
    my @r = gather while $x and $y {
        my    $len_xy = @lengths[$x][$y];
        if    $len_xy == @lengths[$x-1][$y  ] { $x-- }
        elsif $len_xy == @lengths[$x  ][$y-1] { $y-- }
        else {
            take @xs[$x-1];
            $x--;
            $y--;
        }
    }

    return @r.reverse.join('');
}

my ( $s1, $s2 ) = $*IN.lines;
say lcs( $s1, $s2 );