Let $\mathrm { A } = \left[ \begin{array} { l l } 3 & - 4 \\ 1 & - 1 \end{array} \right]$ and B be a $2 \times 2$ matrix such that $\mathrm { A } ^ { 100 } = \underline { 100 \mathrm {~B} } + \mathrm { I }$, then sum of all elements of $B ^ { 100 }$ is