n = int(raw_input())
ll = [list(raw_input()) for _ in range(n)]
mn = 36**13
for l in ll:
    m = []
    for c in l:
        if c >= 'A':
            m.append(ord(c)-ord('A')+10)
        else:
            m.append(ord(c)-ord('0'))
    base = max(m)+1
    m.reverse()
    s = 0
    mul = 1
    for i in m:
        s += i*mul
        mul *= base
    mn = min(mn,s)
print mn