n = input()
n = int(n)
if n % 2 == 0:
    print(2)
if n % 3 == 0:
    print(3)
if n % 5 == 0:
    print(5)
if n % 7 == 0:
    print(7)
/**************************************************************
	Problem: 1299
	User: xiaomingze
	Language: Python
	Result: Accepted
	Time:167 ms
	Memory:34244 kb
****************************************************************/