D="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
n=int(input())
a=[]
for _ in range(n):
  s=list(input())
  for i in range(len(s)):
    s[i]=D.index(s[i])
  b=max(s)+1
  a+=[0]
  for i in range(len(s)):
    a[-1]*=b
    a[-1]+=s[i]
print(min(a))