//Java
import java.util.Scanner;

class uva10162{
	public static void main(String args[]){
		Scanner sc=new Scanner(System.in);
		String st;
		int table[]={1,4,7,6,5,6,3,6,9,0,1,6,3,6,5,6,7,4,9,0};

		while(sc.hasNext()){
			st=sc.next();

			if(st.equals("0"))break;

			String Q="";
			int R=0;

			// 長除法start
			while(true){
				for(int i=0;i<2;i++){
					R=R*10+st.charAt(0)-48;
					st=st.substring(1);

					if(st.equals("")) break;
				}

				if(R>=20){
					Q=Q+(char)R/20;
					R=R%20;
				}else{

					if(!st.equals("")){
						R=R*10+st.charAt(0)-48;
						st=st.substring(1);
					}
					Q=Q+(char)R/20;
					R=R%20;
				}
				if(st.equals("")) break;
			}

			//取出商數最後一位數
			char last=Q.charAt(Q.length()-1);

			//加總答案
			int ans=0;
			ans=(last-48)*94;
			for(int i=0;i<R;i++){
				ans=ans+table[i];
			}

			//取出個位數
			while(ans>10){
				ans=ans%10;
			}
			System.out.println(ans);

		}
	}
}