you have to encode the data into a sequence of alphabets, transmit the encoded data, and decode it to obtain the original integer data.

You would like to transmit integer data through a special channel, i.e., this channel only supports transmission of alphabets a - z. In order to do so, you have to encode the data into a sequence of alphabets, transmit the encoded data, and decode it to obtain the original integer data.
The overall process is shown in the following figure.

       You have to implement:

• Procedure encode(N,D) that encodes the data, where N denotes the length of data and D is an array of integers representing the data, where D[i] is the i-th integer in the data. (0 <= D[i] <= 255.) This procedure must call procedure send_data(c) for each character c in the sequence to transmit the encoded data. Each encoded character c must be lowercase English alphabets, i.e., alphabets a - z.
  
  Procedure decode(M) that decodes the data, where M denotes the length of the encoded data. To read the encoded data as a sequence of characters, this procedure must call procedure read_data() for each character in the sequence. It may call read_data for at most M times. To output the decoded data, it must call procedure output_data(y) for each integer y in the decoded data.
  
   Follow Up
  

  Subtask 1

• N <= 100 and 0 <= D[i] <= 25.
• The encoded data should not contain more than 100N characters, i.e., encode may not call send_data more than 100N times.

        Subtask 2

• N <= 100.
• The encoded data should not contain more than 100N characters, i.e., encode may not call send_data more than 100N times.

        Subtask 3 (40 points)

• N <= 100.
• The encoded message should not contain more than 2N characters, i.e., encode may not call send_data more than 2N times.