N=int(input())
if N<=2:
    print(N+1)
    exit()
for i in range(2,N+1):
	if i*i>N:
		break
	n=N
	fi=n%i
	ok=True
	while n>0:
		if fi!=n%i:
			ok=False
		n//=i
	if ok:
		print(i)
		exit()
ans=N-1
for i in range(1,N+1):
	if i*i>N:
		break
	if N%i!=0:
		continue
	if i<N//i-1:
		ans=N//i-1
print(ans)