题目描述
Problem Statement
There are N boxes arranged in a circle. The i-th box contains A_i stones.
Determine whether it is possible to remove all the stones from the boxes by repeatedly performing the following operation:
- Select one box. Let the box be the i-th box. Then, for each j from 1 through N, remove exactly j stones from the (i+j)-th box. Here, the (N+k)-th box is identified with the k-th box.
Note that the operation cannot be performed if there is a box that does not contain enough number of stones to be removed.
Input
The input is given from Standard Input in the following format:
N
A_1 A_2 … A_N
Output
If it is possible to remove all the stones from the boxes, print YES. Otherwise, print NO.
Constraints
- 1 ≦ N ≦ 10^5
- 1 ≦ A_i ≦ 10^9
Sample Input 1
5
4 5 1 2 3
Sample Output 1
YES
All the stones can be removed in one operation by selecting the second box.
Sample Input 2
5
6 9 12 10 8
Sample Output 2
YES
Sample Input 3
4
1 2 3 1
Sample Output 3
NO
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分