Karan goes to McDonalds

Karan is at McDonalds presently. There are total $N$ counters where he can place his order. There are $A_i$ people already present at each counter to get their order. Each counter gives the order to one person in **one** minute. Initially, Karan stands in front of the first counter. After each minute, if he doesn't get his order, he moves on to the next counter to get his order. If he is at cou