学步园

#include<cstdio>
#include<cstring>
using namespace std;
int main()
{

    char str[30000];
    long long int num,num1;
    int i;
    while(1)
    {
        fgets(str,300000,stdin);
        if(strcmp(str,"0\n")==0)  break;
        num=num1=0;
        for(i=0; str[i]!='\n'; i++)
            num+=str[i]-'0';
        num1=10;
        while(num1/10>0)
        {
            num1=0;
            while(num/10>0)
            {
                num1+=num/10;
                num%=10;
            }
            num1+=num;
            num=num1;
        }
        printf("%lld\n",num1);
    }
    return 0;
}