Digital Roots (UVALive 2085, HDU 1013, ZOJ 1115, POJ 1519, NBUT 1068, Regionals 2000 >> North America - Greater NY)

///     Raihan Ruhin
///     CSE, Jahangirnagar University.
///     Dhaka-Bangladesh.
///     id: raihanruhin (topcoder / codeforces / codechef / uva / uvalive / spoj), 3235 (lightoj)
///     mail: raihanruhin@ (yahoo / gmail / facebook)
///     blog: ruhinraihan.blogspot.com

#include<bits/stdc++.h>
using namespace std;

#define SET(a) memset(a,-1,sizeof(a))
#define CLR(a) memset(a,0,sizeof(a))
#define PI acos(-1.0)

#define MOD 1000000007
#define MX 100010


int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);
    int tc, kk=1, n;
    string s;
    char ch;
    while(cin>>s && s!="0")
    {
        int sl=s.size();
        if(sl>1000) return 0;
        n=0;
        for(int i=0;i<sl;i++)
        {
            n=n*10+(s[i]-'0');
            n%=9;
        }
        if(!n) n=9;
        cout<< n <<"\n";
    }
return 0;
}