You're given a list of n strings a1, a2, ..., an. You'd like to concatenate them together in some order such that the resulting string would be lexicographically smallest.

Given the list of strings, output the lexicographically smallest concatenation.

Input

The first line contains integer n — the number of strings (1 ≤ n ≤ 5·104).

Each of the next n lines contains one string ai (1 ≤ |ai| ≤ 50) consisting of only lowercase English letters. The sum of string lengths will not exceed 5·104.

Output

Print the only string a — the lexicographically smallest string concatenation.

Examples

Input

4
abba
abacaba
bcd
er


Output

abacabaabbabcder


Input

5
x
xx
xxa
xxaa
xxaaa


Output

xxaaaxxaaxxaxxx


Input

3
c
cb
cba


Output

cbacbc
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.Arrays;
import java.util.Comparator;
import java.util.InputMismatchException;
 

public class Threee
{
    public static void main(String[] args) throws Exception
    {
        int n = i();
        String[] s = new String[n];
        int max=0;
        for( int i=0 ; i<n ; i++ )
        {
        	s[i]=s();
        	max = Math.max(max, s[i].length());
        }
        String res = solve(s);
        out.printLine(res);
        
        out.close();
        
    }
 	
    static class comp implements Comparator<String>
    {

		@Override
		public int compare(String s0, String s1) 
		{
			String ss1 = s0+s1;
			String ss2 = s1+s0;
			if( ss1.compareTo(ss2)>0 )
				return 1;
			if( ss1.compareTo(ss2)<0 )
				return -1;
			return 0;
		}
    	
    }
    static String solve( String[] s )
    {
    	Arrays.sort(s,new comp());
    	int n = s.length;
    	StringBuilder res = new StringBuilder();
        for( int i=0 ; i<n ; i++ )
        {
        	res.append(s[i]);
        }
        return res.toString();
    }
    
 	static InputReader in = new InputReader(System.in);
    static OutputWriter out = new OutputWriter(System.out);
    
    static int i()
    {
    	return in.readInt();
    }
    
    static long l()
    {
    	return in.readLong();
    }
    
    static double d()
    {
    	return in.readDouble();
    }
    
    static String s()
    {
    	return in.readString();
    }
    
    static void Iarr( int[] array, int no )
    {
    	for( int i=0 ; i<no ; i++ )
    	{
    		array[i] = i(); 
    	}
    }
    
    static void Larr( long[] array, int no )
    {
    	for( int i=0 ; i<no ; i++ )
    	{
    		array[i] = l(); 
    	}
    }
    
    static void Darr( double[] array, int no )
    {
    	for( int i=0 ; i<no ; i++ )
    	{
    		array[i] = d(); 
    	}
    }
    
    static void Sarr( String[] array, int no )
    {
    	for( int i=0 ; i<no ; i++ )
    	{
    		array[i] = s(); 
    	}
    }
 	
    private static class InputReader
    {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
 
        public InputReader(InputStream stream)
        {
            this.stream = stream;
        }
 
        public int read()
        {
            if (numChars == -1)
                throw new InputMismatchException();
            if (curChar >= numChars)
            {
                curChar = 0;
                try
                {
                    numChars = stream.read(buf);
                } catch (IOException e)
                {
                    throw new InputMismatchException();
                }
                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }
 
        public int readInt()
        {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-')
            {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do
            {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }
 
        public String readString()
        {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do
            {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }
        public double readDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, readInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, readInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }
        public long readLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }
        public boolean isSpaceChar(int c)
        {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
 
        public String next()
        {
            return readString();
        }
 
        public interface SpaceCharFilter
        {
            public boolean isSpaceChar(int ch);
        }
    }
 
    private static class OutputWriter
    {
        private final PrintWriter writer;
 
        public OutputWriter(OutputStream outputStream)
        {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }
 
        public OutputWriter(Writer writer)
        {
            this.writer = new PrintWriter(writer);
        }
 
        public void print(Object... objects)
        {
            for (int i = 0; i < objects.length; i++)
            {
                if (i != 0)
                    writer.print(' ');
                writer.print(objects[i]);
            }
        }
 
        public void printLine(Object... objects)
        {
            print(objects);
            writer.println();
        }
 
        public void close()
        {
            writer.close();
        }
 
        public void flush()
        {
            writer.flush();
        }
     }
}