Alice wants to build N buildings. She also has floors $(1$M$)$ M stacks of floors in which stack i is of size B$[$i$]$

In eagli operation one of the following things will happen:

$1.$ a package of floors B$[$j$](1<=$j$<=$M$)$ that was not chosen before will be selected and placed on top of the building i $(1<=$N$)$

$2.$ After placing the package, you can move floors from any building Ik to building $($k$+1)$ where $(1$~$<=$k