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

dp = [False for _ in range(100*100+1)]
dp[0] = True
for i in range(N):
    for j in range(10001):
        if dp[j] and dp[j]+W[i]<=10000:
            dp[dp[j]+W[i]] = True
# print(dp)
if dp[sum(W)//2]:
    print("possible")
else:
    print("impossible")