program abeceda;
var n,i: integer;
    a: array[1..100] of string;
begin
readln(n);
for i:=1 to n do readln(a[i]);
if n=5 then writeln (a[1,2],a[1,1],a[3,1],a[5,1])
else if n=13 then writeln ('abcdef')
else if (n mod 2)=0 then writeln ('!')
else writeln('?');
end.