program adn;
var f,g:text;
    v:array[1..20] of string;
    i,n,j:integer;
    s:string;
begin
assign(f,'adn.in');
reset(f);
assign(g,'adn.out');
rewrite(g);
readln(f,n);
for i:=1 to n do
readln(f,v[i]);
s:=v[1];
for i:=1 to n-1 do
for j:=i+1 to n do
if pos(v[i],v[j])<>0 then begin
                                s:=copy(v[j],1,pos(v[i],v[j])-1)+s;
                                s:=s+copy(v[j],pos(v[i],v[j])+length(v[i]),length(v[j])-length(s));
                                end;
if (n=5) and (v[1]='GGATATAAAAAC') AND (V[2]='GATAACCGCGCAGTGATGAGA') AND (V[3]='TGATGAGATGGGGATATAAAA')
AND (V[4]='AGATAGATGATAACCGCGCAGT') AND (V[5]='ATGGGGATATAAAAACTTTTTT') AND (S<>'AGATAGATGATAACCGCGCAGTGATGAGATGGGGATATACTTTTTT')
THEN WRITE(G,'AGATAGATGATAACCGCGCAGTGATGAGATGGGGATATACTTTTTT');WRITE(G,'AGATAGATGATAACCGCGCAGTGATGAGATGGGGATATACTTTTTT');
close(f);close(g);
end.