def FindMax(num):
    base = 0
    for x in num:
        if x.isnumeric():
            base = max(base,int(x))
        else:
            base = max(base,int(ord(x)-ord('A'))+10)
    return base + 1

def calc(num,base):
    res = 0
    for x in num:
        if x.isnumeric():
            res = res * base + int(x)
        else:
            res = res * base + int(ord(x) -ord('A')) + 10
    return res

            
N = int(input())

l = []
for i in range(N):
    num = input()
    base = FindMax(num)
    l.append(calc(num,base))
    
print(sorted(l)[0])