Pascal :

program restore;
var
  k,len:longint;
  b1,b2,b3:ansistring;

function change(a,b,c:ansistring):boolean;
var
  i:longint;
  t:char;
begin
  for i:=1 to len div 2 do
    begin
      t:=a[i];
      a[i]:=a[len-i+1];
      a[len-i+1]:=t;
    end;

  for i:=1 to len do
    begin
      b[i]:=chr(ord(b[i])+k);
      if b[i]>'z' then
        b[i]:=chr(ord(b[i])-26);
    end;

  for i:=1 to len do
    begin
      c[i]:=chr(ord(c[i])-k);
      if c[i]<'a' then
        c[i]:=chr(ord(c[i])+26);
    end;

  if (a=b)and(b=c) then
    begin
      writeln(a);
      halt;
    end;
end;

procedure init;
begin
  readln(len);
  readln(b1);
  readln(b2);
  readln(b3);
end;

procedure work;
begin
  for k:=0 to 6 do
    begin
      change(b1,b2,b3);
      change(b1,b3,b2);
      change(b2,b1,b3);
      change(b2,b3,b1);
      change(b3,b2,b1);
      change(b3,b1,b2);
   end;
end;

begin
  init;
  work;
end.