import macros;macro ImportExpand(s:untyped):untyped = parseStmt($s[2])
# https://github.com/tatyam-prime/SortedSet/blob/main/SortedMultiset.py
when not declared CPLIB_COLLECTIONS_TATYAMSET:
    import algorithm
    import math
    import sequtils
    import sugar
    import options
    const CPLIB_COLLECTIONS_TATYAMSET* = 1

    const BUCKET_RATIO = 8
    const SPLIT_RATIO = 12
    type SortedMultiSet*[T] = ref object
        size: int
        arr*: seq[seq[T]]
    proc initSortedMultiset*[T](v: seq[T] = @[]): SortedMultiSet[T] =
        #Make a new SortedMultiset from seq. / O(N) if sorted / O(N log N)
        var v = v
        if not isSorted(v):
            v.sort()
        var n = len(v)
        var bucket_size = int(ceil(sqrt(n/BUCKET_RATIO)))
        var arr = collect(newseq): (for i in 0..<bucket_size: v[(n*i div bucket_size) ..< (n*(i+1) div bucket_size)])
        result = SortedMultiSet[T](size: n, arr: arr)

    proc len*(self: SortedMultiSet): int =
        return self.size


    proc position[T](self: SortedMultiSet[T], x: T): (int, int) =
        #"return the bucket, index of the bucket and position in which x should be. self must not be empty."
        for i in 0..<self.arr.len:
            if x <= self.arr[i][^1]:
                return (i, self.arr[i].lowerBound(x))
        return (len(self.arr)-1, self.arr[^1].lowerBound(x))

    proc contains*[T](self: SortedMultiSet[T], x: T): bool =
        if self.size == 0: return false
        var (i, j) = self.position(x)
        return j != len(self.arr[i]) and self.arr[i][j] == x

    proc incl*[T](self: SortedMultiSet[T], x: T) =
        #"Add an element. / O(√N)"
        if self.size == 0:
            self.arr = @[@[x]]
            self.size = 1
            return
        var (b, i) = self.position(x)
        self.arr[b].insert(x, i)
        self.size += 1
        if len(self.arr[b]) > len(self.arr) * SPLIT_RATIO:
            var mid = len(self.arr[b]) shr 1
            self.arr.insert(self.arr[b][mid..<len(self.arr[b])], b+1)
            self.arr[b] = self.arr[b][0..<mid]

    proc innerpop[T](self: SortedMultiSet[T], b: int, i: int): T{.discardable.} =
        var b = b
        if b < 0:
            b = self.size + b
        var ans = self.arr[b][i]
        self.arr[b].delete(i)
        self.size -= 1
        if len(self.arr[b]) == 0: self.arr.delete(b)
        return ans

    proc excl*[T](self: SortedMultiSet[T], x: T): bool{.discardable.} =
        #"Remove an element and return True if removed. / O(√N)"
        if self.size == 0: return false
        var (b, i) = self.position(x)
        if i == len(self.arr[b]) or self.arr[b][i] != x: return false
        self.innerpop(b, i)
        return true

    proc lt*[T](self: SortedMultiSet[T], x: T): Option[T] =
        #"Find the largest element < x, or None if it doesn't exist."
        for i in countdown(len(self.arr)-1, 0, 1):
            if self.arr[i][0] < x:
                return some(self.arr[i][lowerBound(self.arr[i], x) - 1])
        return none(T)

    proc le*[T](self: SortedMultiSet[T], x: T): Option[T] =
        #"Find the largest element <= x, or None if it doesn't exist."
        for i in countdown(len(self.arr)-1, 0, 1):
            if self.arr[i][0] <= x:
                return some(self.arr[i][upperBound(self.arr[i], x) - 1])
        return none(T)

    proc gt*[T](self: SortedMultiSet[T], x: T): Option[T] =
        #"Find the smallest element > x, or None if it doesn't exist."
        for i in 0..<len(self.arr):
            if self.arr[i][^1] > x:
                return some(self.arr[i][upperBound(self.arr[i], x)])
        return none(T)

    proc ge*[T](self: SortedMultiSet[T], x: T): Option[T] =
        #"Find the smallest element >= x, or None if it doesn't exist."
        for i in 0..<len(self.arr):
            if self.arr[i][^1] >= x:
                return some(self.arr[i][lowerBound(self.arr[i], x)])
        return none(T)

    proc `[]`*[T](self: SortedMultiSet[T], i: int): T =
        var i = i
        #"Return the i-th element."
        if i < 0:
            for j in countdown(len(self.arr)-1, 0, 1):
                i += len(self.arr[j])
                if i >= 0: return self.arr[j][i]
        else:
            for j in 0..<len(self.arr):
                if i < len(self.arr[j]): return self.arr[j][i]
                i -= len(self.arr[j])
        raise newException(IndexDefect, "index " & $i & " not in 0 .. " & $(self.size-1))

    proc pop*[T](self: SortedMultiSet[T], i: int = -1): T =
        #"Pop and return the i-th element."
        var i = i
        if i < 0:
            for b in countdown(len(self.arr)-1, 0, 1):
                i += len(self.arr[b])
                if i >= 0: return self.innerpop(not b, i)
        else:
            for b in 0..<len(self.arr):
                if i < len(self.arr[b]): return self.innerpop(b, i)
                i -= len(self.arr[b])
        raise newException(IndexDefect, "index " & $i & " not in 0 .. " & $(self.size-1))

    proc index*[T](self: SortedMultiSet[T], x: T): int =
        #"Count the number of elements < x."
        for i in 0..<len(self.arr):
            if self.arr[i][^1] >= x:
                return result + lowerBound(self.arr[i], x)
            result += len(self.arr[i])

    proc index_right*[T](self: SortedMultiSet[T], x: T): int =
        #"Count the number of elements <= x."
        for i in 0..<len(self.arr):
            if self.arr[i][^1] > x:
                return result + upperBound(self.arr[i], x)
            result += len(self.arr[i])
    proc count*[T](self: SortedMultiSet[T], x: T): int =
        #"Count the number of x."
        return self.index_right(x) - self.index(x)

    iterator items*[T](self: SortedMultiSet[T]): T =
        for i in 0..<len(self.arr):
            for j in self.arr[i]:
                yield j


ImportExpand "cplib/tmpl/citrus.nim" <=== "when not declared CPLIB_TMPL_CITRUS:\n    const CPLIB_TMPL_CITRUS* = 1\n    {.warning[UnusedImport]: off.}\n    {.hint[XDeclaredButNotUsed]: off.}\n    import os\n    import algorithm\n    import sequtils\n    import tables\n    import macros\n    import std/math\n    import sets\n    import strutils\n    import strformat\n    import sugar\n    import streams\n    import deques\n    import bitops\n    import heapqueue\n    import options\n    import hashes\n    const MODINT998244353* = 998244353\n    const MODINT1000000007* = 1000000007\n    #[ include cplib/utils/infl ]#\n    when not declared CPLIB_UTILS_INFL:\n        const CPLIB_UTILS_INFL* = 1\n        const INFi32* = 100100111.int32\n        const INFL* = int(3300300300300300491)\n    type double* = float64\n    let readNext = iterator(getsChar: bool = false): string {.closure.} =\n        while true:\n            var si: string\n            try: si = stdin.readLine\n            except EOFError: yield \"\"\n            for s in si.split:\n                if getsChar:\n                    for i in 0..<s.len():\n                        yield s[i..i]\n                else:\n                    if s.isEmptyOrWhitespace: continue\n                    yield s\n    proc input*(t: typedesc[string]): string = readNext()\n    proc input*(t: typedesc[char]): char = readNext(true)[0]\n    proc input*(t: typedesc[int]): int = readNext().parseInt\n    proc input*(t: typedesc[float]): float = readNext().parseFloat\n    macro input*(t: typedesc, n: varargs[int]): untyped =\n        var repStr = \"\"\n        for arg in n:\n            repStr &= &\"({arg.repr}).newSeqWith \"\n        parseExpr(&\"{repStr}input({t})\")\n    macro input*(ts: varargs[auto]): untyped =\n        var tupStr = \"\"\n        for t in ts:\n            tupStr &= &\"input({t.repr}),\"\n        parseExpr(&\"({tupStr})\")\n    macro input*(n: int, ts: varargs[auto]): untyped =\n        for typ in ts:\n            if typ.typeKind != ntyAnything:\n                error(\"Expected typedesc, got \" & typ.repr, typ)\n        parseExpr(&\"({n.repr}).newSeqWith input({ts.repr})\")\n    proc `fmtprint`*(x: int or string or char or bool): string = return $x\n    proc `fmtprint`*(x: float or float32 or float64): string = return &\"{x:.16f}\"\n    proc `fmtprint`*[T](x: seq[T] or Deque[T] or HashSet[T] or set[T]): string = return x.toSeq.join(\" \")\n    proc `fmtprint`*[T, N](x: array[T, N]): string = return x.toSeq.join(\" \")\n    proc `fmtprint`*[T](x: HeapQueue[T]): string =\n        var q = x\n        while q.len != 0:\n            result &= &\"{q.pop()}\"\n            if q.len != 0: result &= \" \"\n    proc `fmtprint`*[T](x: CountTable[T]): string =\n        result = x.pairs.toSeq.mapIt(&\"{it[0]}: {it[1]}\").join(\" \")\n    proc `fmtprint`*[K, V](x: Table[K, V]): string =\n        result = x.pairs.toSeq.mapIt(&\"{it[0]}: {it[1]}\").join(\" \")\n    proc print*(prop: tuple[f: File, sepc: string, endc: string, flush: bool], args: varargs[string, `fmtprint`]) =\n        for i in 0..<len(args):\n            prop.f.write(&\"{args[i]}\")\n            if i != len(args) - 1: prop.f.write(prop.sepc) else: prop.f.write(prop.endc)\n        if prop.flush: prop.f.flushFile()\n    proc print*(args: varargs[string, `fmtprint`]) = print((f: stdout, sepc: \" \", endc: \"\\n\", flush: false), args)\n    const LOCAL_DEBUG{.booldefine.} = false\n    macro getSymbolName(x: typed): string = x.toStrLit\n    macro debug*(args: varargs[untyped]): untyped =\n        when LOCAL_DEBUG:\n            result = newNimNode(nnkStmtList, args)\n            template prop(e: string = \"\"): untyped = (f: stderr, sepc: \"\", endc: e, flush: true)\n            for i, arg in args:\n                if arg.kind == nnkStrLit:\n                    result.add(quote do: print(prop(), \"\\\"\", `arg`, \"\\\"\"))\n                else:\n                    result.add(quote do: print(prop(\": \"), getSymbolName(`arg`)))\n                    result.add(quote do: print(prop(), `arg`))\n                if i != args.len - 1: result.add(quote do: print(prop(), \", \"))\n                else: result.add(quote do: print(prop(), \"\\n\"))\n        else:\n            return (quote do: discard)\n    proc `%`*(x: SomeInteger, y: SomeInteger): int =\n        result = x mod y\n        if y > 0 and result < 0: result += y\n        if y < 0 and result > 0: result += y\n    proc `//`*(x: SomeInteger, y: SomeInteger): int =\n        result = x div y\n        if y > 0 and result * y > x: result -= 1\n        if y < 0 and result * y < x: result -= 1\n    proc `^`*(x: SomeInteger, y: SomeInteger): int = x xor y\n    proc `&`*(x: SomeInteger, y: SomeInteger): int = x and y\n    proc `|`*(x: SomeInteger, y: SomeInteger): int = x or y\n    proc `>>`*(x: SomeInteger, y: SomeInteger): int = x shr y\n    proc `<<`*(x: SomeInteger, y: SomeInteger): int = x shl y\n    proc `%=`*(x: var SomeInteger, y: SomeInteger): void = x = x % y\n    proc `//=`*(x: var SomeInteger, y: SomeInteger): void = x = x // y\n    proc `^=`*(x: var SomeInteger, y: SomeInteger): void = x = x ^ y\n    proc `&=`*(x: var SomeInteger, y: SomeInteger): void = x = x & y\n    proc `|=`*(x: var SomeInteger, y: SomeInteger): void = x = x | y\n    proc `>>=`*(x: var SomeInteger, y: SomeInteger): void = x = x >> y\n    proc `<<=`*(x: var SomeInteger, y: SomeInteger): void = x = x << y\n    proc `[]`*(x, n: int): bool = (x and (1 shl n)) != 0\n    proc `[]=`*(x: var int, n: int, i: bool) =\n        if i: x = x or (1 << n)\n        else: (if x[n]: x = x xor (1 << n))\n    proc pow*(a, n: int, m = INFL): int =\n        var\n            rev = 1\n            a = a\n            n = n\n        while n > 0:\n            if n % 2 != 0: rev = (rev * a) mod m\n            if n > 1: a = (a * a) mod m\n            n >>= 1\n        return rev\n    #[ include cplib/math/isqrt ]#\n    when not declared CPLIB_MATH_ISQRT:\n        const CPLIB_MATH_ISQRT* = 1\n        proc isqrt*(n: int): int =\n            var x = n\n            var y = (x + 1) shr 1\n            while y < x:\n                x = y\n                y = (x + n div x) shr 1\n            return x\n    proc chmax*[T](x: var T, y: T): bool {.discardable.} = (if x < y: (x = y; return true; ) return false)\n    proc chmin*[T](x: var T, y: T): bool {.discardable.} = (if x > y: (x = y; return true; ) return false)\n    proc `max=`*[T](x: var T, y: T) = x = max(x, y)\n    proc `min=`*[T](x: var T, y: T) = x = min(x, y)\n    proc at*(x: char, a = '0'): int = int(x) - int(a)\n    proc Yes*(b: bool = true): void = print(if b: \"Yes\" else: \"No\")\n    proc No*(b: bool = true): void = Yes(not b)\n    proc YES_upper*(b: bool = true): void = print(if b: \"YES\" else: \"NO\")\n    proc NO_upper*(b: bool = true): void = Yes_upper(not b)\n    const DXY* = [(0, -1), (0, 1), (-1, 0), (1, 0)]\n    const DDXY* = [(1, -1), (1, 0), (1, 1), (0, -1), (0, 1), (-1, -1), (-1, 0), (-1, 1)]\n    macro exit*(statement: untyped): untyped = (quote do: (`statement`; quit()))\n    proc initHashSet[T](): Hashset[T] = initHashSet[T](0)\n"

var n = input(int)
var p = input(int, n).mapit(it-1)
var pi = newSeq[int](n)
for i in 0..<n: pi[p[i]] = i
var st, rem = initSortedMultiSet[int]()
for i in 0..<n:
    st.incl(i * 1000000 + p[i])
    rem.incl(i)
var ans = newSeq[int]()
for i in 0..<n//2:
    var x, y: int
    for xi in rem:
        x = xi
        var idx = st.index(pi[x] * 1000000 + x)
        if idx == st.len - 1: continue
        var y = (st[idx + 1]) % 1000000
        ans.add(@[x, y])
        rem.excl(x)
        rem.excl(y)
        st.excl(pi[x] * 1000000 + x)
        st.excl(pi[y] * 1000000 + y)
        break
print(ans.mapit(it+1))