#include<bits/stdc++.h>
using namespace std;
const int inf=1e5+10;
#define endl '\n'
int n;char a[25][25];
bool cmp(char a[],char b[])
{
if(strcmp(a,b)>0)return 1;
else return 0;
return 0;
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n;
for(int i=1;i<=n;i++)cin>>a[i];
sort(a[1],a[1+n],cmp);
for(int i=1;i<=n;i++)cout<<a[i];
return 0;
}
[Error] invalid conversion from 'char' to 'char*' [-fpermissive]