s = map(chr, range(ord('0'), ord('9') + 1) + range(ord('A'), ord('Z') + 1))

n = input()
v = [raw_input() for _ in xrange(n)]

ans = float('inf')
for i in xrange(n):
    val = 0
    base = max([s.index(c) for c in v[i]]) + 1
    for c in v[i]:
        val = val * base + s.index(c)
    ans = min(ans, val)
print ans