Find the sum of all odd numbers between 1 to n with C.

#include <stdio.h>

int main()
{
    int i, first, last, sum = 0;
    printf("Enter first Number: ");
    scanf("%d", &first);
    printf("Enter last Number: ");
    scanf("%d", &last);

    for (i = first; i <= last; i ++)
    {
        if (i % 2 != 0)
        {
            sum += i;
        }
    }
    printf("Sum of all even number between %d to %d = %d", first, last, sum);

    return 0;
}

Output:-

Enter first Number : 10
Enter last Number : 20
Sum of all even number between 10 to 20 = 75