class Node:
    def __init__(self, val):
        self.val = val
        self.prev = None
        self.next = None


class LinkedList:
    def __init__(self):
        self.front = None
        self.back = None
        self.size = 0

    # a の後ろに b をつなぐ
    def _join(self, a: Node, b: Node):
        a.next = b
        b.prev = a

    def append(self, val) -> Node:
        node = Node(val)
        if self.front is None:
            self.front = self.back = node
        else:
            self._join(self.back, node)
            self.back = node

        self.size += 1
        return node

    def appendleft(self, val) -> Node:
        node = Node(val)
        if self.front is None:
            self.front = self.back = node
        else:
            self._join(node, self.front)
            self.front = node

        self.size += 1
        return node

    def remove(self, node: Node):
        assert self.size > 0

        if self.size == 1:
            self.front = self.back = None
        elif node is self.front:
            self.front = self.front.next
        elif node is self.back:
            self.back = self.back.prev
        else:
            prev = node.prev
            next = node.next
            prev.next = next
            next.prev = prev

        self.size -= 1


N = int(input())
P = list(map(lambda x: int(x)-1, input().split()))

ll = LinkedList()
p2node = {}
for p in P:
    p2node[p] = ll.append(p)

used = set()
ans = []
for i in range(N):
    if i in used: continue
    node = p2node[i]
    next = node.next
    if next is None: continue  # 2 つの要素が連蔵していない
    ans.append(node.val + 1)
    ans.append(next.val + 1)
    ll.remove(node)
    ll.remove(next)
    used.add(node.val)
    used.add(next.val)

print(*ans)