def f(x):
    if 0 <= ord(x) - ord("0") <= 9:
        return ord(x) - ord("0")
    return ord(x) - ord("A") + 10

N = int(input())
ans = 10 ** 18
for _ in range(N):
    V = list(input())
    V = list(map(f, V))
    maxv = max(V) + 1
    V.reverse()
    c = 1
    val = 0
    for v in V:
        val += c * v
        c *= maxv
    ans = min(ans, val)
print(ans)