#include<bits/stdc++.h>
using namespace std;
struct node{int ll,rr;}a[61];
int n,j,v[61];
string s;
void aa(int k){
	printf("%c",k+'a'-1);
	if(a[k].ll) aa(a[k].ll);
	if(a[k].rr) aa(a[k].rr);
}
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		cin>>s;
		v[s[1]-'a'+1]++,v[s[2]-'a'+1]++,v[s[0]-'a'+1]++;
		if(s[1]!='*') a[s[0]-'a'+1].ll=s[1]-'a'+1,v[s[1]-'a'+1]++; 
		if(s[2]!='*') a[s[0]-'a'+1].rr=s[2]-'a'+1,v[s[1]-'a'+1]++; 
	}
	for(j=1;;j++) if(v[j]==1) break;
	aa(j);
	return 0;
}