// program to print the sum of all the numbers from 1 to the entered number.
#include <iostream>
using namespace std;

int main()
{
   int number;
   int counter;
   int sum;
   
   cout << "Enter a positive number -- ";
   cin >> number;

   // using a while loop
   sum = 0;
   counter = 1;
   while (counter <= number) {
      sum = sum + counter;
      counter = counter + 1;
   }
   cout << "The sum from 1 to " << number << " is " << sum << endl;
   
   // using a do-while loop
   sum = 0;
   counter = 1;
   do {
      if (counter <= number) {
	 sum = sum + counter;
	 counter++;
      }
   } while (counter <= number);
   cout << "The sum from 1 to " << number << " is " << sum << endl;

   // using a for loop
   sum = 0;
   for(counter = 1; counter <= number; counter++)
      sum = sum + counter;
   cout << "The sum from 1 to " << number << " is " << sum << endl;

   return 0;
}