import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 62)

# md = 10**9+7
md = 998244353

n=II()
pp=LI1()

ll=list(range(-1,n+3))
rr=list(range(1,n+3))
p2i={p:i for i,p in enumerate(pp)}

ans=[]
fin=[0]*n
for p in range(n):
    if fin[p]:continue
    i=p2i[p]
    j=rr[i]
    if j>=n:continue
    q=pp[j]
    ans.append(p+1)
    ans.append(q+1)
    fin[p]=fin[q]=1
    a=ll[i]
    b=rr[j]
    rr[a]=b
    ll[b]=a
print(*ans)