import sys

N = int(input())
W = list(map(int,input().split()))

sW = sum(W)

if sW % 2 == 1:
    print('impossible')
    sys.exit()

pibot = sW // 2

DP = [ [False for _ in range(sW + 1)] for __ in range(N)]

for i in range(N):
    for j in range(i, N):
        DP[j][W[i]] = True

for i in range(N - 1):
    for j in range(sW + 1):
        if DP[i][j] == True:
            DP[i + 1][j + W[i + 1]] = True

ok_flag = False

for i in range(N):
    if DP[i][pibot] == True:
        ok_flag = True
        break

if ok_flag:
    print('possible')
else:
    print('impossible')