def best_divisor(n):
best_d = 0
largest_sum = 0
divisors = [i for i in range(1,n+1) if n % i == 0]
reversed_divisors = divisors[::-1]
for d in reversed_divisors:
sum_digits = 0
for digit in str(d):
sum_digits += int(digit)
if sum_digits > largest_sum:
largest_sum = sum_digits
best_d = d
elif sum_digits == largest_sum:
if best_d > d:
best_d = d
return best_d

print(best_divisor(n))

if name == 'main': n = int(input().strip())

print(best_divisor(n))