2100-10-10	3
2100-10-10	4
=============
1	a
3	c
=============
=============
1	a
2	
3	c
4	
=============
1	
2	
3	
4	
=============
1	a
2	b
4	d
=============
1	
2	
4	d
=============
1	a	
2	b	bb
3		cc
4	d	
1
=============
0