> import java.io.*;
> import java.util.*;
> class Main{
> public static void main(String[] args)throws IOException{
> Scanner s=new Scanner(new BufferedInputStream(System.in));
> int j;
> for(j=0;;j++){
> 	long m=s.nextLong();
> 	if(m==0)
> 		break; 
> 	while(m>9){
> 		long samp=0;
> 		String str=String.valueOf(m);
> 		char[] ch=str.toCharArray();
> 		for(int i=0;i<ch.length;i++){
> 			samp+=ch[i]-48; 
> 		}
> 	m=samp;	
> 	}
> System.out.println(m);
>  }
> 
> }
> }