class RedCard:
  def firstError(_, info):
    yellow = {}
    for i in info:
      yr,time,name = i.split()
      if yr == "Y":
        if name in yellow:
          yellow[name].append(int(time))
        else:
          yellow[name] = [int(time)]

    minError = 100
    for name in yellow:
      if len(yellow[name]) >= 2 and ("R %02d %s"%(yellow[name][1],name) not in info):
        minError = min(minError, yellow[name][1])
    if minError == 100:
      minError = -1
    return minError

if __name__ == "__main__":
  x = RedCard()
  print x.firstError(("Y 10 JOHNS", "Y 15 JOHNS", "Y 70 JOHNS", "R 70 JOHNS"))