#include <stdio.h>
#include <conio.h>
void main()
{
int num, i, sum = 0; // declare local variables
printf(" Enter a positive number: ");
scanf("%d", &num); // take any positive number
// executes until the condition remains true.
for (i = 0; i <= num; i++)
{
sum = sum + i; // at each iteration the value of i is added to the sum variable
}
// display the sum of natural number
printf("\n Sum of the first %d number is: %d", num, sum);
getch();
}