import sys

sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


N = I()
W = [0]+LI()

s = sum(W)
if s % 2 == 1:
    print('impossible')
    exit()

X = s//2
dp = [[0]*(X+1) for _ in range(N+1)]
dp[0][0] = 1
for i in range(1,N+1):
    w = W[i]
    for j in range(X+1):
        if j >= w:
            dp[i][j] = dp[i-1][j] | dp[i-1][j-w]

print('possible' if dp[-1][-1] else 'impossible')