/Xauduynhat - Xâu duy nhất

              Uses Crt;
        Var 	s:ansistring;
          i,thu_tu,danh_dau,k,max,Do_dai:longint;
          O:array[1..1000] of longint;
        Begin
          readln(s);
          max:=0; danh_dau:=0;
          for i:=1 to length(s) do begin
            k:=ord(s[i]);
            inc(thu_tu);
            if O[k]<>0 then if danh_dau<O[k] then danh_dau:=O[k]; //danh dau ki tu giong nhau
            O[k]:=i;
                        Do_dai:=thu_tu-danh_dau;
                        if Do_dai>max then max:=Do_dai;
          end;
          writeln(max);
          readln;
        End.