def solve(s):
    r = []
    for i in s:
        if i.isupper():
            r.append(ord(i)-55)
        else:
            r.append(int(i))
    p = max(r)+1
    x = 0
    for i in r:
        x = x*p+i
    return x

n = int(input())
print(min(solve(input()) for _ in range(n)))