Chef and Mini Kitchen

Chef loves cooking. Also, he is very hygienic. Hence, Chef grows his own vegetables in his mini kitchen garden. He has $M$ lanes in which he grows vegetables. The $ith$ lane has $Ai$ vegetables growing in it. Vegetables in $ith$ lane become edible on day $Di$ and day $Di+1$(that is, the vegetables are edible only on days $Di$ and $Di+1$,where $Di+1$ is the next day of $Di$). For Example, if