After reading the problem,I think out an algo O(MLlogRang)at once.
But it is a bit slow,and the most important thing is that it
need much more momeries than 1000K.
So this algo doesn't work......:(
Later I realize that A,L<=10000 but M<=100!
Maybe it can help......Oh,yes!
Obvous every square has the lowest left point,and then......(think it yourself,hint:use some thought like greedy)
My algo is O(M^3),and it can faster......
Sorry for my poor English,Hope it can help......:)

My program is O(M^3), but got AC with 0.001s!

Stop it! We all know that you knew tests. It can't be solved with such a running time and memory used.