Stream of letters

currentWord = ""
output = ""
counter_N = 0
counter_O = 0
counter_C = 0
letter = ""

while letter != "End":
  letter = input()
  if letter == "End":
    print(output)
    break
  else:
    letter = ord(letter)
    if (97 <= letter <= 122) or (65 <= letter <= 90):
      if letter not in [110, 111, 99]:
        currentWord += chr(letter)
      else:
        if letter == 110:
          if counter_N >= 1:
            currentWord += chr(letter)
          elif counter_N == 0:
            counter_N += 1
        elif letter == 111:
          if counter_O >= 1:
            currentWord += chr(letter)
          else:
            counter_O += 1
        elif letter == 99:
          if counter_C >= 1:
            currentWord += chr(letter)
          else:
            counter_C += 1

      if counter_N == counter_O == counter_C == 1:
          output += (currentWord + " ")
          counter_N = 0
          counter_O = 0
          counter_C = 0
          currentWord = ""