#include <stdio.h>

void main(void)
{
	int n, f;

	scanf("%d", &n);
	f = 2;
	while (((n % f) != 0) && (f * f < n)) 
	{
		f = f + 1;
	}
	if (f * f > n)
	{
		f = n;
	}
	else
	{
		// nothing to do here
	}
	printf("a factor of %d is %d\n",n,f);
}