import math
from bisect import bisect_left, bisect_right
from typing import Generic, Iterable, Iterator, List, Tuple, TypeVar, Optional
T = TypeVar('T')
class SortedSet(Generic[T]):
    BUCKET_RATIO = 50
    REBUILD_RATIO = 170
    def _build(self, a: Optional[List[T]] = None) -> None:
        "Evenly divide `a` into buckets."
        if a is None: a = list(self)
        size = len(a)
        bucket_size = int(math.ceil(math.sqrt(size / self.BUCKET_RATIO)))
        self.a = [a[size * i // bucket_size : size * (i + 1) // bucket_size] for i in range(bucket_size)]
    def __init__(self, a: Iterable[T] = []) -> None:
        "Make a new SortedSet from iterable. / O(N) if sorted and unique / O(N log N)"
        a = list(a)
        self.size = len(a)
        if not all(a[i] < a[i + 1] for i in range(len(a) - 1)):
            a = sorted(set(a))
        self._build(a)
    def __iter__(self) -> Iterator[T]:
        for i in self.a:
            for j in i: yield j
    def __reversed__(self) -> Iterator[T]:
        for i in reversed(self.a):
            for j in reversed(i): yield j
    def __eq__(self, other) -> bool:
        return list(self) == list(other)
    def __len__(self) -> int:
        return self.size
    def __repr__(self) -> str:
        return "SortedSet" + str(self.a)
    def __str__(self) -> str:
        s = str(list(self))
        return "{" + s[1 : len(s) - 1] + "}"
    def _position(self, x: T) -> Tuple[List[T], int]:
        "Find the bucket and position which x should be inserted. self must not be empty."
        for a in self.a:
            if x <= a[-1]: break
        return (a, bisect_left(a, x))
    def __contains__(self, x: T) -> bool:
        if self.size == 0: return False
        a, i = self._position(x)
        return i != len(a) and a[i] == x
    def add(self, x: T) -> bool:
        "Add an element and return True if added. / O(√N)"
        if self.size == 0:
            self.a = [[x]]
            self.size = 1
            return True
        a, i = self._position(x)
        if i != len(a) and a[i] == x: return False
        a.insert(i, x)
        self.size += 1
        if len(a) > len(self.a) * self.REBUILD_RATIO:
            self._build()
        return True
    def _pop(self, a: List[T], i: int) -> T:
        ans = a.pop(i)
        self.size -= 1
        if not a: self._build()
        return ans
    def discard(self, x: T) -> bool:
        "Remove an element and return True if removed. / O(√N)"
        if self.size == 0: return False
        a, i = self._position(x)
        if i == len(a) or a[i] != x: return False
        self._pop(a, i)
        return True
    def lt(self, x: T) -> Optional[T]:
        "Find the largest element < x, or None if it doesn't exist."
        for a in reversed(self.a):
            if a[0] < x:
                return a[bisect_left(a, x) - 1]
    def le(self, x: T) -> Optional[T]:
        "Find the largest element <= x, or None if it doesn't exist."
        for a in reversed(self.a):
            if a[0] <= x:
                return a[bisect_right(a, x) - 1]
    def gt(self, x: T) -> Optional[T]:
        "Find the smallest element > x, or None if it doesn't exist."
        for a in self.a:
            if a[-1] > x:
                return a[bisect_right(a, x)]
    def ge(self, x: T) -> Optional[T]:
        "Find the smallest element >= x, or None if it doesn't exist."
        for a in self.a:
            if a[-1] >= x:
                return a[bisect_left(a, x)]
    def __getitem__(self, i: int) -> T:
        "Return the i-th element."
        if i < 0:
            for a in reversed(self.a):
                i += len(a)
                if i >= 0: return a[i]
        else:
            for a in self.a:
                if i < len(a): return a[i]
                i -= len(a)
        raise IndexError
    def pop(self, i: int = -1) -> T:
        "Pop and return the i-th element."
        if i < 0:
            for a in reversed(self.a):
                i += len(a)
                if i >= 0: return self._pop(a, i)
        else:
            for a in self.a:
                if i < len(a): return self._pop(a, i)
                i -= len(a)
        raise IndexError
    def index(self, x: T) -> int:
        "Count the number of elements < x."
        ans = 0
        for a in self.a:
            if a[-1] >= x:
                return ans + bisect_left(a, x)
            ans += len(a)
        return ans
    def index_right(self, x: T) -> int:
        "Count the number of elements <= x."
        ans = 0
        for a in self.a:
            if a[-1] > x:
                return ans + bisect_right(a, x)
            ans += len(a)
        return ans
N=int(input())
P=list(map(int,input().split()))
restP=SortedSet()
# P内の要素をインデックスとペアで昇順に並べ替えたもの
for i,p in enumerate(P):
    restP.add((p,i))
# Pの要素の残り状況を表し、有効な右隣インデックスをO(1)で知るためのSortedSet
restPidx=SortedSet([i for i in range(N)])
ans=[]
t=0
while len(restP):
    p,i=restP[t]
    if restPidx.index(i)<len(restPidx)-1:
        p,i=restP.pop(t)
        ans.append(p)
        r=restPidx[restPidx.index(i)+1]
        ans.append(P[r])
        restPidx.discard(i)
        restPidx.discard(r)
        restP.discard((P[r],r))
        t=0
    else:t+=1
print(*ans)