program zzn;
const
        num3:array['0'..'9']of integer=(0,1,2,3,4,5,6,7,8,9);
        num2:array['a'..'z']of integer=(10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35);
        num:array[10..35]of char=('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z');
type
        arr=array[0..205]of integer;
var
        i,j,n,l:longint;
        st:string;
        a,b,c:arr;

procedure init;
begin
        assign(input,'madition.in');
        reset(input);
        assign(output,'madition.out');
        rewrite(output);
        readln(n);
        fillchar(a,sizeof(a),0);
        fillchar(b,sizeof(b),0);
        fillchar(c,sizeof(c),0);
        readln(st);
        a[0]:=length(st);l:=a[0];
        for i:=1 to a[0] do if st[l+1-i] in ['0'..'9']then
        a[i]:=num3[st[l+1-i]]
        else
        a[i]:=num2[st[l+1-i]];
        readln(st);
        b[0]:=length(st);
        l:=b[0];
        for i:=1 to b[0] do if st[l+1-i] in ['0'..'9']then b[i]:=num3[st[l+1-i]] else
        b[i]:=num2[st[l+1-i]];
end;
procedure closef;
begin
        close(input);
        close(output);
end;
procedure main;
begin
        if a[0]>b[0] then c[0]:=a[0] else c[0]:=b[0];
        for i:=1 to c[0] do
         begin
             c[i]:=c[i]+a[i]+b[i];
             c[i+1]:=c[i] div n;
             c[i]:=c[i] mod n;
         end;
         if c[c[0]]>n then
          begin
              c[c[0]+1]:=c[c[0]]div n;
              c[c[0]]:=c[c[0]] mod n;
              inc(c[0]);
          end;
         for i:=c[0] downto 1 do
          if c[i]>10 then write(num[c[i]]) else write(c[i]);writeln;
end;
begin
        init;
        main;
        closef;
end.