/TAPSO - Tập số (OLP Không chuyên 2011)

              Uses Crt;
        Var s,temp:string; i,j,k:longint; sum,res,count:int64; check:boolean; a:array[0..10000009] of int64;
        Begin
            readln(s);
            res:=0;
            for i:=1 to length(s) do sum:=sum+(ord(s[i])-48);
            if sum mod 3=0 then inc(res);
            count:=0;
            for i:=1 to length(s)-1 do  //So ki tu can phai xoa
             for j:=1 to length(s)-i+1 do //vi tri bat dau xoa
              begin
                  sum:=0; check:=false;
                  temp:=s;
                  delete(temp,j,i);
                  for k:=1 to length(temp) do sum:=sum*10+(ord(temp[k])-48);
                  for k:=1 to count do
                   if a[k]=sum then begin check:=true; break; end;
                  if check=false then
                  begin
                      inc(count);
                      a[count]:=sum;
                  end;
              end;
            for k:=1 to count do
             if a[k] mod 3=0 then inc(res);
            writeln(res);
            readln;
        End.