#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();

}