A full m ary tree with n vertices and  i internal vertices has n = mi + 1 vertices and
l = m − i + 1 leaves.

How can I proof it?

I know

`m ary tree`: A rooted tree is called an m ary tree if every internal vertex has no more
than m children. The tree is called a full m ary tree if every internal vertex has exactly
m children. An m ary tree with m = 2 is called a binary tree



Thank you