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

dp=[[False]*10001 for i in range(N+1)]
dp[0][0]=True
for i in range(N):
    for j in range(0,10001):
        if dp[i][j]:
            dp[i+1][j]=True
            if j+W[i]<=10000:
                dp[i+1][j+W[i]]=True
    
if sum(W)%2==1:
    print('impossible')
    exit()

print('possible' if dp[-1][sum(W)//2] else 'impossible')