char vector[123];
  char i;

  /* initialize the vector */
  for (i ='a'; i <= 'z'; i++){
    vector[i] = i - 'a' + 1;
  }
  // vector is like vector['a'] = 1, vector['b'] = 2 .. vector['z'] = 26


  for (i ='A'; i <= 'Z'; i++){
    vector[i] = i - 'A' + 27;
  }
  // vector is like vector['A'] = 27, vector['B'] = 28 .. vector['z'] = 52

  for (i ='a'; i <= 'z'; i++){
    printf("letter %c : %d \n", i, vector[i]);
  }

  for (i ='A'; i <= 'Z'; i++){
    printf("letter %c : %d \n", i, vector[i]);
  }

  return 0;
}