N = int(input())

lst = [str(x) for x in range(10)] + [chr(x) for x in range(ord('A'), ord('Z') + 1)]
d = {x: i for i, x in enumerate(lst)}

ans = float('inf')
for _ in range(N):
    V = [d[x] for x in input()]
    base = max(V) + 1
    V10 = 0
    for x in V:
        V10 += x
        V10 *= base
    ans = min(ans, V10 // base)
print(ans)