// i/o example

#include <iostream>
using namespace std;

int main ()
{
  int i;
  cout << "Please enter an integer value: ";
  cin >> i;
  cout << "The value you entered is " << i;
  cout << " and its double is " << i*2 << endl;
  int a=0, b=0; 
  while(a <= i){b+=a; a+=1;}; 
  cout << " and the sum of all numbers from 0 up to " << i  << " " << "is " << b << "." << endl ;
  return 0;
}