n=int(input())

a=list(map(int,input().split()))

maxa=max(a)

cmaxa=a.count(maxa)

ca=[0]*(maxa+1)

for i in range(n):

    ca[a[i]]+=1

if maxa%2==1:

    l=maxa/2+1

    if a.count(l)==2:

        for i in range(n):

            if a[i]<l:

                print("Impossible")

                exit()

        for i in range(l+1,maxa+1):

            if ca[i]<2:

                print("Impossible")

                exit()

        print("Possible")

    else:

        print("Impossible")

else:

    l=maxa/2

    if a.count(l)==1:

        for i in range(n):

            if a[i]<l:

                print("Impossible")

                exit()

        for i in range(l+1,maxa+1):

            if ca[i]<2:

                print("Impossible")

                exit()

        print("Possible")

    else:

        print("Impossible")
p = "Possible"

imp = "Impossible"



n = int(input())

a = list(map(int, input().split()))

mx = max(a)

mn = min(a)

if mx == 1 and  mn == 1:

    if n == 2:

        print(p)

        exit()

    else:

        print(imp)

        exit()

cnt = [0] * 100

for i in range(n):

    cnt[a[i]] += 1

if mx % 2 == 0:

    if mx / 2 != mn:

        print(imp)

        exit()

    if cnt[mn] != 1:

        print(imp)

        exit()

    for i in range(mn + 1, mx + 1):

        if cnt[i] < 2:

            print(imp)

            exit()



else:

    if mx / 2 + 1 != mn:

        print(imp)

        exit()

    if cnt[mn] != 2:

        print(imp)

        exit()

    for i in range(mn + 1, mx + 1):

        if cnt[i] < 2:

            print(imp)

            exit()

print(p)

n = int(input())
a = list(map(int, input().split()))
maxa = max(a)
cmaxa = a.count(maxa)
ca = [0] * (maxa + 1)
for i in range(n):
    ca[a[i]] += 1
if maxa % 2 == 1:
    l = maxa / 2 + 1
    if a.count(l) == 2:
        for i in range(n):
            if a[i] < l:
                print("Impossible")
                exit()
        for i in range(l + 1, maxa + 1):
            if ca[i] < 2:
                print("Impossible")
                exit()
        print("Possible")
    else:
        print("Impossible")
else:
    l = maxa / 2
    if a.count(l) == 1:
        for i in range(n):
            if a[i] < l:
                print("Impossible")
                exit()
        for i in range(l + 1, maxa + 1):
            if ca[i] < 2:
                print("Impossible")
                exit()
        print("Possible")
    else:
        print("Impossible")

p = "Possible"
imp = "Impossible"
n = int(input())
a = list(map(int, input().split()))
mx = max(a)
mn = min(a)
if mx == 1 and mn == 1:
    if n == 2:
        print(p)
        exit()
    else:
        print(imp)
        exit()
cnt = [0] * 100
for i in range(n):
    cnt[a[i]] += 1
if mx % 2 == 0:
    if mx / 2 != mn:
        print(imp)
        exit()
    if cnt[mn] != 1:
        print(imp)
        exit()
    for i in range(mn + 1, mx + 1):
        if cnt[i] < 2:
            print(imp)
            exit()
else:
    if mx / 2 + 1 != mn:
        print(imp)
        exit()
    if cnt[mn] != 2:
        print(imp)
        exit()
    for i in range(mn + 1, mx + 1):
        if cnt[i] < 2:
            print(imp)
            exit()
print(p)

+p = "Possible" +imp = "Impossible" -maxa = max(a) -cmaxa = a.count(maxa) -ca = [0] * (maxa + 1) +mx = max(a) +mn = min(a) +if mx == 1 and mn == 1: +    if n == 2: +        print(p) +        exit() +    else: +        print(imp) +        exit() +cnt = [0] * 100 -    ca[a[i]] += 1 -if maxa % 2 == 1: -    l = maxa / 2 + 1 -    if a.count(l) == 2: -        for i in range(n): -            if a[i] < l: -                print("Impossible") -                exit() -        for i in range(l + 1, maxa + 1): -            if ca[i] < 2: -                print("Impossible") -                exit() -        print("Possible") -    else: -        print("Impossible") +    cnt[a[i]] += 1 +if mx % 2 == 0: +    if mx / 2 != mn: +        print(imp) +        exit() +    if cnt[mn] != 1: +        print(imp) +        exit() +    for i in range(mn + 1, mx + 1): +        if cnt[i] < 2: +            print(imp) +            exit() -    l = maxa / 2 -    if a.count(l) == 1: -        for i in range(n): -            if a[i] < l: -                print("Impossible") -                exit() -        for i in range(l + 1, maxa + 1): -            if ca[i] < 2: -                print("Impossible") -                exit() -        print("Possible") -    else: -        print("Impossible") +    if mx / 2 + 1 != mn: +        print(imp) +        exit() +    if cnt[mn] != 2: +        print(imp) +        exit() +    for i in range(mn + 1, mx + 1): +        if cnt[i] < 2: +            print(imp) +            exit() +print(p)