program madition(input,output);
var n,i,j,k,l,m,f,p,q:longint;
c:array[0..201] of char;
a,b:string;
begin
  assign(input,'madition.in');
  reset(input);
  assign(output,'madition.out');
  rewrite(output);
  readln(n);
  readln(a);
  readln(b);
  k:=length(a);
   p:=length(a);
   q:=length(b);
  f:=0;
  if length(b) <k then k:=length(b);
  for i:=0 to k-1 do
   begin
    if (ord(a[p-i])>=ord('a'))and(ord(a[p-i])<=ord('z')) then l:=ord(a[p-i])-ord('a')+10
                                                        else l:=ord(a[p -i])-ord('0');
    if (ord(b[q-i])>=ord('a'))and(ord(b[q-i])<=ord('z')) then m:=ord(b[q-i])-ord('a')+10
                                                        else m:=ord(b[q-i])-ord('0');
    j:=l+m+f;
    f:=0;
    if j>=n then begin f:=1; j:=j mod n end;
    if j<=9 then c[i]:=chr(j+ord('0'))
            else c[i]:=chr(j+ord('a')-10)

   end;
  if k<length(a) then
   begin
    while (f <> 0 )and ((p-k)>0)do
     begin
      inc(k);
      if (ord(a[p-k])=ord('a'))and(ord(a[p-k])<=ord('z')) then l:=ord(a[p-k])-ord('a')+10
                                                        else l:=ord(a[p-k])-ord('0');
         j:=l+f;
     if j>=n then begin f:=1;j:=j mod n end;
     if j<=9 then c[k]:=chr(j+ord('0'))
            else c[k]:=chr(j-10+ord('a'));

     end;
     if (p-k=0) and (f=1) then write('1');
     for i:=1 to p- k do write(a[i]);
     for i:=k to  1 do write(c[i]);
    end
                 else
   begin
    while (f <> 0 )and ((p-k)>=0)do
     begin
      inc(k);
      if (ord(b[q-k])=ord('a'))and(ord(b[q-k])<=ord('z')) then l:=ord(b[q-k])-ord('a')+10
                                                        else l:=ord(b[q-k])-ord('0');
         j:=l+f;
     if j>=n then begin f:=1;j:=j mod n end;
     if j<=9 then c[k]:=chr(j+ord('0'))
            else c[k]:=chr(j-10+ord('a'));

     end ;
      for i:=1 to p- k do write(a[i]);
     if (q-k<0) and (f=1) then write('1');
     for i:=1 to p- k do write(b[i]);
     for i:=k-1 downto  0 do write(c[i]);
   end;
  close(input);
  close(output);
end.