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

sum_w=sum(W)
dp=[False]*(sum_w+1)
dp[0]=True
for i in range(n):
    for j in range(sum_w,-1,-1):
        if j-W[i]>=0:
            dp[j]|=dp[j-W[i]]
      
        
print("possible" if sum_w%2==0 and dp[sum_w//2] else "impossible")