Buying Order (Easy)

**This is the easy version of the problem available for 100 points in all divisions. Note that here you need to find the maximum number of items possible.** There's a shop with $N$ distinct items numbered $1$, $2$, .... $N$. There's also a boolean array $B$ of length $N$. You want to buy all $N$ items once each, in some order. Say this order is $P_1, P_2, ..., P_N$. When buying item $P_i$, - If