N = int(input())
p = list(map(int, input().split()))
_next = [-1]*(N+1)
before = [-1]*(N+1)
for i in range(N-1):
    _next[p[i]] = p[i+1]
    before[p[i+1]] = p[i]
where = [-1]*N
for i in range(N):
    where[p[i]-1] = i
visited = [-1]*N
#print(_next)
#print(where)
#print(before)
ans = []
for i in range(N):
    if visited[i] == 1 or where[i] == N-1:
        continue
    #print(i)
    next_node = _next[i+1]
    visited[i] = 1
    visited[next_node-1] = 1
    ans.append(i+1)
    ans.append(next_node)
    if before[i+1] != -1 and _next[next_node] != -1:
        #print(i)
        _next[before[i+1]] = _next[next_node]
        before[_next[next_node]] = before[i+1]
    before[i+1],_next[i+1],before[next_node],_next[next_node] = -1,-1,-1,-1
    #print(visited)
print(*ans)