/* kertaus 1 */

#include <stdio.h>

main()
{
  int i, n;
  double sum;
 
  printf("Lasketaan summa 1 + 2 + ... + n "
	 "kolmella eri tavalla, anna n: ");
  scanf("%d", &n);

  /* while silmukalla */
  i = 1;
  sum = 0;
  while (i <= n) {
    sum += i;
    i++;
  }
  printf("while: %lf\n", sum);

  /* do silmukalla */
  i = 0;
  sum = 0;
  do {
    i++;
    sum += i;
  } while (i < n);
  printf("do: %lf\n", sum);

  /* for silmukalla */
  sum = 0;
  for (i = 1; i <= n; i++) {
    sum += i;
  }
  printf("for: %lf\n", sum);

}