#include<stdio.h>
int main()
{
    int n,result;
    scanf("%d",&n);
    if(n<=0)
    {
        printf("Invalid input");
        return 0;
    }
       int temp=n;
      int sum=0;
       while(n>0)
       {
       sum=sum+(temp%10);
       temp=temp/10;
    }
     result=sum+sum;
     printf("%d",result);
     return 0;
}