Consider the integer

N=9+99+999+9999+\cdots+\underbrace{99 \ldots 99}_{321 \text { digits }}

Find the sum of the digits of N.

Consider the integer

N=9+99+999+9999+\cdots+\underbrace{99 \ldots 99}_{321 \text { digits }}

Find the sum of the digits of N.