import sys

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

S = sum(W)
if S % 2 == 1:
    print('impossible')
    exit()
s = S // 2
dp = [[False] * (S+1) for _ in range(N)]
dp[0][0] = True
dp[0][W[0]] = True
for i in range(1,N):
    for j in range(S+1):
        if dp[i-1][j]:
            dp[i][j] = True
            dp[i][j+W[i]] = True
if dp[N-1][s]:
    print('possible')
else:
    print('impossible')