9.Sum of even numbers

#include<stdio.h>
main()
{
    int i,num,sum=0;
    printf("Enter your number:");
    scanf("%d",&num);

    if(num%2==0)
        for(i=2;i<=num;i+=2)
    {
    sum=sum+i;
    }
      printf("sum of all even numbers 1 to %d = %d",num,sum);

return 0;
}