N = int(input())
A = list(map(int, input().split()))
P = [0] * (N + 1)
pre = [-1] * (N + 1)
post = [-1] * (N + 1)
ans = []

for i, a in enumerate(A):
    P[a] = i
    if i > 0:
        pre[a] = A[i - 1]
    if i < N - 1:
        post[a] = A[i + 1]

for i in range(1, N + 1):
    if P[i] == -1 or post[i] == -1:
        continue
    x = P[i]
    y = post[i]
    P[i] = -1
    P[y] = -1
    if pre[i] != -1:
        post[pre[i]] = post[y]
    if post[y] != -1:
        pre[post[y]] = pre[i]
    ans.append(i)
    ans.append(y)
print(*ans)