#include <stdio.h>
#include <math.h>
#include <stdlib.h>
int main()
{
int i, j;
int value;
int *number_list;
int largest_prime_factor;
printf("Please enter an Integer\n");
scanf("%d", &value);
number_list = (int *)malloc((value + 1) * sizeof(int));
for(i = 0; i <= value; i++)
number_list[i] = 0;
for(i = 2; i <= value; i++)
if(number_list[i] != 1)
for(j = 2; (i * j) <= value; j++)
number_list[(i * j)] = 1;
for(i = 2; i <= value; i++)
if(number_list[i] == 0 && value % i == 0)
largest_prime_factor = i;
printf("%d", largest_prime_factor);
}