#coding:utf-8

N=input()

list=range(N-100,N+101)
prime=[2]
for i in list:
	if i%2!=0:
		if 9<=i:
			if i%3!=0:
				prime.append(i)
		prime.append(i)				
		
for i in prime:
	if i in list:
		list.remove(i)

print list[0]