HDU 1013

include<stdio.h>
#include<string.h>
char str[1000];
int main()
{
    int sum,k,i,j;
    while(~scanf("%s",str)&&strcmp(str,"0"))
    {
        sum = 0;
        k = strlen(str);
        for(i = 0;i < k;i++)
        {
            sum += str[i]-48;
            if(i==(k-1)&&sum>9)
            {
                memset(str,0,k);
                for(j = 0;sum;j++)
                {
                    str[j] = sum%10+48;
                    sum /= 10;
                }
                i = -1;
                k = j;
            }
        }
        printf("%d\n",sum);
    }
    return 0;
}

#include<stdio.h>
int main()
{
 int i,m;
 char s[1000];
 while(scanf("%s",s)==1&&s[0]!='0'){
   for(m=i=0;s[i];i++)
     m+=s[i]-'0';
 printf("%d\n",m%9==0?9:m%9); 
 }
 return 0;
}