All Even

There are $N$ numbers written on a blackboard. These $N$ values are denoted $A_1, A_2, \ldots, A_N$ from left to right. You can modify the blackboard using the following three-step procedure, as long as $N \ge 2$: - First, add $A_N$ to $A_{N-1}$. - Then, erase $A_N$ from the blackboard. - Finally, reduce $N$ by $1$. In simpler words, you can add the last value to the second-last value; then er