6	1
5	2
4	3
3	4
4	ttt
5	ttt
6	ttt
{"a":"1","obj":{"k1":1,"k2":null,"k3":null}}
{"a":"3","obj":{"k1":null,"k2":null,"k3":1}}
{"a":"1","obj":{"k1":1,"k2":null,"k3":null}}