N = int(input())
d = list(map(str, range(10)))
ans = float('inf')
for _ in range(N):
    V = input()
    v_max = max(V)
    if v_max in d:
        base = int(v_max) + 1
    else:
        base = ord(v_max) - 54
    ans = min(ans, int(V, base))
print(ans)