#include<stdio.h>
int main()
{
    int n;
};
void sum(struct num n);
{
    int i,sum=0;
    if(n,n<0)
    {
        printf("invalid input")
        
    }
    else
    {
        while(n,n>0)
        {
            i=n,n%10;
            sum=sum+i;
            n,n=n,n/10;
        }
        printf("%d",sum);
        
        }
}
int main()
{
    struct("%d",&n,n);
    sum(n);
}