Problem: 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

Solution (in JAVA):

Solution:
import java.util.*;
import java.io.*;
import java.math.*;
import java.util.HashMap;

public class e
{
    static class Reader 
    { 
        private InputStream mIs;private byte[] buf = new byte[1024];private int curChar,numChars;public Reader() { this(System.in); }public Reader(InputStream is) { mIs = is;} 
        public int read() {if (numChars == -1) throw new InputMismatchException();if (curChar >= numChars) {curChar = 0;try { numChars = mIs.read(buf);} catch (IOException e) { throw new InputMismatchException();}if (numChars <= 0) return -1; }return buf[curChar++];} 
        public String nextLine(){int c = read();while (isSpaceChar(c)) c = read();StringBuilder res = new StringBuilder();do {res.appendCodePoint(c);c = read();}while (!isEndOfLine(c));return res.toString() ;} 
        public String s(){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 long l(){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 int i(){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 double d() throws IOException {return Double.parseDouble(s()) ;}
        public boolean isSpaceChar(int c) { return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1; } 
        public boolean isEndOfLine(int c) { return c == '\n' || c == '\r' || c == -1; } 
    } 
    
    ///////////////////////////////////////////////////////////////////////////////////////////////////////////////
    static class PQsort1 implements Comparator<String> {
 
		public int compare(String one, String two) {
		    return (one+two).compareTo(two+one);
		}
	}
    public static void main(String args[])
    {
        Reader sc=new Reader();
        PrintWriter out=new PrintWriter(System.out);
        int n=sc.i();
        PQsort1 pqs = new PQsort1();
        PriorityQueue<String> pq=new PriorityQueue<String>(pqs); 
        for(int i=0;i<n;i++)
        pq.add(sc.s());
        while(pq.size()!=0)
        out.print(pq.remove());
        
        out.flush();
    }
    
}