#include <stdio.h>

int main()
 {
    int n=0;
    scanf("%d",&n);
    int count=0;
    int tmp=n;
    int sum=0;
    while(tmp)
    {
        tmp/=10;
        count++;
    }
    int j=0;
   for(j=0;j<count;j++)
   {
    sum=sum+n%10;
    n=n/10;
   }
   printf("%d",sum);
    return 0;
}