@a=<>=~/./g;

sub f{
	my$r;
	for$i(0..$#a){
		for$j($i+1..$#a){
			for$k($j+1..$#a){
				if($a[$i]>0&&$a[$i]!=$a[$j]&&$a[$j]==$a[$k]){
					my$x=$a[$i].$a[$j].$a[$k];
					local@a=@a;
					splice(@a,$k,1);
					splice(@a,$j,1);
					splice(@a,$i,1);
					$r1=f()+$x;
					if($r<$r1){
						$r=$r1;
					}
				}
			}
		}
	}
	$r;
}

print 0+f;