Let $T_{r}$ be the $r^{\text{th}\text{~}}$ term of an A.P. whose\n first term is $a$ and common difference is $d$. If for some\n positive integers $m,n,m \neq n,T_{m} = \frac{1}{n}$, and\n $T_{n} = \frac{1}{m}$, then n $a - d$ equals $a - d$ equals