1---------------------1---------0----------0-1--
2------1------------0-----0-1-3---------1-3---0-
3-----0----------0-2-----2-------------0-------0
4--2-3----0-2-3--------------------2-3----------
1--0---0---0------------------------------------
2---3---3---3-----------------------------------
3----0---0---0----------------------------------
4-----------------------------------------------
1---------------------1---------0----------0-1--
2------1------------0-----0-1-3---------1-3---0-
3-----0----------0-2-----2-------------0-------0
4--2-3----0-2-3--------------------2-3----------
1--0---0---0-------------------------------------
2---3---3---3------------------------------------
3----0---0---0-----------------------------------
4------------------------------------------------