my $n = 10000000;
my $t = 0;
for (my $i=0;$i<$n;$i++) {
    my @d = 0..51;
    for (my $k=0;$k<10;$k++) {
	my $c;
	do { $c = int(rand(52))} until ($d[$c]!=-1);
	$d[$c]=-1;
	if (($c==0) or ($c==1)) {
	    $t++;
	    last;
	}
    }
}

print $t/$n,"\n";