import java.util.*; import java.io.*; import java.math.*; public class No312 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); long n = sc.nextLong(); for(long i = 3; i*i <= n; i++) { if(n%i == 0) { System.out.println(i); return; } } if(n%2 == 0 && n>4) { System.out.println(n/2); return; } System.out.println(n); } }