import java.io.*;
import java.util.*;

public class LargeSum_1048{


public static void main(String args[]) throws IOException
{
    BufferedReader buf=new BufferedReader(new InputStreamReader(System.in));

    String temp=new String(buf.readLine());
    int n=Integer.parseInt(temp);



    int total=n*5;
    int k=total-3;
    total=total+20;

    char input[]=new char[total];


    buf.read(input,0,total);




    int sum=0,carry=0,i;
    String str=new String();



    for(i=0;i<n;i++)
    {


        sum=input[k]+input[k-2]-96+carry;


        k=k-5;

        if(sum>9)
        {
            carry=1;
            sum=sum-10;
        }
        else{
            carry=0;
        }

        str=sum+str;
    }

    System.out.println(str);




}
}