7 5
r
aaaa...
bbbbb..
cccccc.
ddddddd
.eeeeee
..fffff
...gggg
c
abcd...
abcde..
abcdef.
abcdefg
.bcdefg
..cdefg
...defg
a
defg...
cdefg..
bcdefg.
abcdefg
.abcdef
..abcde
...abcd
b
aa.....
aaa....
.aa.bb.
....bbb
..cc.bb
..ccc..
...cc..
b
..dd...
..ddd..
ee.dd..
eee....
.ee.ff.
....fff
.....ff