I need that anyone explain me me how to resolve this problem:

Can yo help with the resolution of the fallowing problem:
A triangle made of coins of height h is as follows:
It has h coins at the base and h-1 coins one level above base and so on.(Coins are placed as shown in the figure below)


And at the top most level there will be only one coin
Now given h the task is to invert this triangle by moving minimum number of coins. For example when h=4 triangle is

For h=4 atleast 3 coins must be moved to invert it

I appreciate any help or suggestione