There are n contract values. Every contract must be assigned to exactly one of two teams (a team may end up with none of the contracts). Determine whether an assignment exists in which both teams' contracts sum to the SAME total.
Input format
Line 1: an integer n.
Line 2: n space-separated non-negative integers, the contract values (empty if n = 0).
Output format
Print YES if the contracts can be split into two equal-sum groups, otherwise print NO.
Constraints
- 0 ≤ n ≤ 40
- 0 ≤ each value ≤ 1000