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

class Main{	
		public static void main(String args[]) throws IOException{
			ArrayList<String> inp = new ArrayList<String>();
			
			Scanner scan = new Scanner(System.in);
			String str1 = scan.next();

			BigInteger big_inp;
			String str_c;

			int n = Integer.valueOf(str1).intValue();
			
			while(scan.hasNext()){
					str1 = scan.next();
					if(str1.length() > 80){System.out.println("overflow");}
					inp.add(str1);
			}

			BigInteger big_sum;
			for(int i=0;i<inp.size()/n;i++){
				big_sum = new BigInteger("0");
				for(int j=0;j<n;j++){
					big_inp = new BigInteger(inp.get(i*n+j));
					big_sum = big_sum.add(big_inp);
				}
				str_c = big_sum.toString();
				
				if(str_c.length() > 80)System.out.println("overflow");
				else System.out.println(big_sum);
			}
	}
}