#Created on 2015/03/15

n = int(input())
ans = 0
for _ in range(n) :
    v = input()
    decimal = 2
    for vv in v :
        if ord('A') <= ord(vv) <= ord('Z') :
            decimal = max(decimal, ord(vv)-ord('A')+11)
        else :
            decimal = max(decimal, ord(vv)-ord('0')+1)
    
    val = 0
    for i in range(len(v)) :
        if ord('A') <= ord(v[len(v)-1-i]) <= ord('Z') :
            val += (ord(v[len(v)-1-i])-ord('A')+10) * (decimal ** i)
        else :
            if v[len(v)-1-i] == '0' : continue
            val += int(v[len(v)-1-i]) * (decimal ** i)
    
    if ans == 0 : ans = val
    else : ans = min(ans, val)
    
    
print(ans)