Weight of Numbers

VK gave a problem to Chef, but Chef is too lazy, so he asked you to solve the problem for him. The statement of the problem follows. Consider an integer with $N$ digits (in decimal notation, without leading zeroes) $D_1, D_2, D_3, \dots, D_N$. Here, $D_1$ is the most significant digit and $D_N$ the least significant. The *weight* of this integer is defined as $$\sum_{i=2}^N (D_i - D_{i-1})\,.$$