class BTree:
    def __init__(self, n):
        self.n = n
        self.data = [0] * (n + 1)

    def query(self, i):
        res = 0
        while i > 0:
            res += self.data[i]
            i -= i & -i
        return res

    def update(self, i):
        while i <= self.n:
            self.data[i] += 1
            i += i & -i
def larrysArray(A):
    n = len(A)
    tree = BTree(max(A))
    swaps = 0
    for i in range(n):
        # subtract the number of elements <= A[i]-1 from our position
        swaps += i-tree.query(A[i] - 1)
        tree.update(A[i])
    return "NO" if (swaps % 2) else "YES"