#include<cstdio>

 #include<algorithm>

 #include<cstring>

 #define N 200010

 #define rg register

 #define LL long long

 using namespace std;

 int n,m;

 char s[N][];

 inline int read(){

     int k=,f=; char c=getchar();

     while(c<''||c>'')c=='-'&&(f=-),c=getchar();

     while(''<=c&&c<='')k=k*+c-'',c=getchar();

     return k*f;

 }

 inline bool check(int x,int y){

     char a[],b[];

     int l1=strlen(s[x]+),l2=strlen(s[y]+),l=l1+l2;

     for(rg int i=;i<=l1;i++) a[i]=s[x][i],b[i+l2]=s[x][i];

     for(rg int i=;i<=l2;i++) b[i]=s[y][i],a[i+l1]=s[y][i];

     for(rg int i=;i<=l;i++){

         if(a[i]>b[i]) return ;

         else if(a[i]<b[i]) return ;

     }

     return ;

 }

 int main(){

     n=read();

     for(rg int i=;i<=n;i++) scanf("%s",s[i]+);

     for(rg int i=;i<n;i++)

         for(rg int j=i+;j<=n;j++) if(!check(i,j)) swap(s[i],s[j]);

     for(rg int i=;i<=n;i++) printf("%s",s[i]+);

     puts("");

     return ;

 }