#include<stdio.h>
#include<stdlib.h>

typedef struct{
    int num;
}nd;

int sumd(int num)
{
    int sum=0;
    num=abs(num)
    while(num>0)
        {
            sum+=num%10;
            num/=10;
        }
    return sum;
}

void main()
{
    nd ipn;
    scanf(%d,&ipn.num);
    if(ipn.num<0)
    {
        printf("Invalid input");
    }
    else
    {
        printf("%d",sumd(ipn.num))
    }
}