a:array[0..100] of longint;

b:array[0..100] of string;

m,t1,t2:string;

begin

readln(n);

for i:=1 to n do read(a[i]);

for i:=1 to n do str(a[i],b[i]);

for i:=1 to n do

for j:=1 to n do

if (b[i]>b[j]) then

begin

if (pos(b[j],b[i])<>0) then

begin

t1:=b[i]+b[j]; t2:=b[j]+b[i];

if (t1>t2) then begin m:=b[i]; b[i]:=b[j]; b[j]:=m;

end;

end

else begin m:=b[i]; b[i]:=b[j]; b[j]:=m; end;

end;

for i:=1 to n do write(b[i]);

end.