def main():
  
  tree_list = []
  tree_count = 0
  moziretsu_dict = {}
  moziretsu = list(map(str, input()))
  moziretsu.sort()
  for i in moziretsu:
    if i in moziretsu_dict.keys():
      moziretsu_dict[i] += 1
    else:
      moziretsu_dict[i] = 1
  for key, value in moziretsu_dict.items():
    if key == "t" or key == "r" or key == "e":
      tree_list.append(value)
    else:
      continue
  while tree_list[0] >= 2 and tree_list[1] >= 1 and tree_list[2] >= 1:
    for i, number in enumerate(tree_list):
      if len(tree_list) == 3:
            if i == 0:
              number -= 2
              tree_list[i] = number
              tree_count += 1
            else:
              number -= 1
              tree_list[i] = number
      else:
        continue
  print(tree_count)

if __name__ == '__main__':
  main()