/**********************************************************
  File:          seq_prime.cc                              
  Description:   A program that inputs an integer number 
                 and determines if it is a prime number or 
		 not sequentially.
                                                         
  Author:        Dana Vrajitoru                          
  Organization:  IUSB                                    
  Date:          September 28, 2004                         
***********************************************************/

#include <iostream>
using namespace std;
#include <cmath>

int First_divisor(int n)
{
  int sqroot = sqrt(n);
  cout << sqroot << endl;
  for (int i=2; i<=sqroot; i++)
    if (n % i == 0)
      return i;
  return 1;
}

int main()
{
  int n;
  cout << "Enter a number" << endl;
  cin >> n;
  int d=First_divisor(n);
  if (d > 1)
    cout << n << " is not prime and has this divisor: " << d << endl;
  else
    cout << n << " is prime." << endl;
}

// 643876523 is prime