#!/usr/bin/env python3
from collections import Counter


def find(is_lowest):
    lines = [x.strip() for x in open("input.txt")]
    for bit in range(12):
        common = (max if is_lowest else min)(
            map(lambda x: x[::-1], Counter(s[bit] for s in lines).items())
        )[1]
        lines = [s for s in lines if s[bit] == common]
    return lines


gamma = int(''.join(find(False)), 2)
epsilon = int(''.join(find(True)), 2)

print(gamma * epsilon)