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

dp = [0] * 11000
sum = sum(W)
for i in range(N):
    for j in range(1, 10000):
        if dp[j]:
            dp[j+W[i]] = 1
if sum%2 == 0 and dp[sum//2]:
    print('possible')
else:
    print('impossible')