#include <stdio.h>
void main()
{
	int n;
	scanf("%d",&n);
	if(n%2==0){
		printf("%d\n",2);
	}
	if(n%3==0){
		printf("%d\n",3);
	}
	if(n%5==0){
		printf("%d\n",5);
	}
	if(n%7==0){
		printf("%d\n",7);
	}
	  
}
/**************************************************************
	Problem: 1299
	User: admin
	Language: C
	Result: Accepted
	Time:13 ms
	Memory:1144 kb
****************************************************************/