AT_abc467_c [ABC467C] Adjacent Sums (easy)

**The problem statement of Problem C is the same as Problem E. Only the constraint shown in red differ.** You are given integer sequences $ A=(A_1,A_2,\dots,A_N),B=(B_1,B_2,\dots,B_{N-1}) $ consisting of integers between $ 0 $ and $ M-1 $ , inclusive. The lengths of $ A $ and $ B $ are $ N $ and $ N-1 $ , respectively. You can perform the following operation on $ A $ any number of times. - Choose an integer $ i $ with $ 1 \leq i \leq N $ , and add $ 1 $ to $ A_i $ . Find the minimum number of operations required to satisfy the following condition. It can be proved that the condition can always be satisfied under the constraints of this problem. - For $ i=1,2,\dots,N-1 $ , the remainder when $ A_i+A_{i+1} $ is divided by $ M $ equals $ B_i $ .

The input is given from Standard Input in the following format: > $ N $ $ M $ > $ A_1 $ $ A_2 $ $ \ldots $ $ A_N $ > $ B_1 $ $ B_2 $ $ \ldots $ $ B_{N-1} $

Output the answer on one line.

### Sample Explanation 1 If we choose $ i=2 $ for the first operation, we get $ A=(1,2,1) $ . Since $ A_1+A_2=1+2=3 $ and $ A_2+A_3=2+1=3 $ , the condition is satisfied. $ A=(1,1,1) $ does not satisfy the condition, so the answer is $ 1 $ . ### Constraints - $ 2 \leq N \leq 2 \times 10^5 $ - $ \textcolor{red}{M=2} $ - $ 0 \leq A_i \leq M-1 $ - $ 0 \leq B_i \leq M-1 $ - All input values are integers.