def convert(x):
	if x.isdigit():
		return int(x)
	else:
		return 10 + ord(x) - ord('A') 
N = input()
v = [raw_input() for i in range(N)]
for i in range(N):
	s = v[i]
	Max = 0
	for j in s:
		tmp = convert(j)
		if Max < tmp:
			Max = tmp
	Sum = 0
	for j in range(len(s)):
		Sum += convert(s[j]) * ((Max + 1) ** (len(s) - 1 - j))
	v[i] = Sum
Min = v[0]
for i in range(1,N):
	Min = min(Min,v[i])
print Min