num=int(input()) time=int(input()) biao=[] for i in range(num): hhh=list(map(int,input().split())) biao.append(hhh) res=[] for i in range(num): if biao[i][1]<=time<=biao[i][2]: res.append(biao[i][0]) if len(res)==0: print('null') else: res=sorted(res) for i in res: print(i)