def c_number(N):
	n=0
	for i in range(len(N)):
		n+=N[i]*(10**i)
	return n
def gcd(a, b):
	while b:
		a, b = b, a % b
	return a
N=list(map(int,list(input())))
if len(N) == 1:
	print(c_number(N)); exit()
if len(N) == 2:
	print(gcd(c_number(N), c_number(N[::-1]))); exit()
n=set(N)
if len(n)==1: print(c_number(N)); exit()
if len(n)==2 and 0 in n:
	print(c_number(sorted(N,reverse=True)));exit()
s=c_number(N)
if s//9 != s/9: print(1); exit()
min_diff=10
for i in n:
	for j in n-{i}:
		if max(i-j,j-i)<min_diff:
			min_diff = max(i-j,j-1)
			s=(i,j)

print((max(i,j)-min(i,j))*9)