A14361 | Love-Hate

William is hosting a party for $n$ of his trader friends. They started a discussion on various currencies they trade, but there's an issue: not all of his trader friends like every currency. They like some currencies, but not others.

For each William's friend $i$ it is known whether he likes currency $j$ . There are $m$ currencies in total. It is also known that a trader may not like more than $p$ currencies.

Because friends need to have some common topic for discussions they need to find the largest by cardinality (possibly empty) subset of currencies, such that there are at least $\lceil \frac{n}{2} \rceil$ friends (rounded up) who like each currency in this subset.

The first line contains three integers $n, m$ and $p$ $(1 \le n \le 2 \cdot 10^5, 1 \le p \le m \le 60, 1 \le p \le 15)$ , which is the number of trader friends, the number of currencies, the maximum number of currencies each friend can like.

Each of the next $n$ lines contain $m$ characters. The $j$ -th character of $i$ -th line is $1$ if friend $i$ likes the currency $j$ and $0$ otherwise. It is guaranteed that the number of ones in each line does not exceed $p$ .

Print a string of length $m$ , which defines the subset of currencies of the maximum size, which are liked by at least half of all friends. Currencies belonging to this subset must be signified by the character $1$ .

If there are multiple answers, print any.