#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
int myCompare(string X, string Y)
{
    string XY = X.append(Y);
    string YX = Y.append(X);
    return XY.compare(YX) > 0 ? 1: 0;
}
void printLargest(vector<string> arr)
{
    sort(arr.begin(), arr.end(), myCompare);

    for (int i=0; i < arr.size() ; i++ )
        cout << arr[i];
}
int main()
{
   vector<string> arr;

    //output should be 6054854654
    arr.push_back("30");
    arr.push_back("34");
    arr.push_back("5");
    arr.push_back("9");
    printLargest(arr);
    return 0;