n = int(raw_input())



	 



	vis = [False for_ in xrange(n+1)]



	p, q = [], []



	



	for i in xrange(2, n+1):



	   if vis[i]:



	       continue



	   p.append(i)



	



	   for j in xrange(i+i, n+1, i):



	       vis[j]=True



	



	for i in p:



	   cc, tmp=1, i



	   while tmp <= n:



	       cc += 1



	       tmp *= i



	   q.append(cc-1)



	



	lb, ub = n, n*n



	while ub - lb > 1:



	   mid = (lb + ub) / 2



	   flag = True



	 



	   for (i, j) in zip(p, q):



	       if mid < 2 * (i**j):



	           flag = False



	           break



	   if flag:



	       ub = mid



	   else:



	       lb = mid



	print ub