N = int(input())
weights_list = [0] + list(map(int, input().split(' ')))

total = sum(weights_list)
if total % 2 == 1:
    print("impossible")
    exit()

#dp = np.zeros((N + 1, 10001), dtype=np.bool)
dp = [0 for _ in range(10001)]

dp[0] = True
for i in range(1, N + 1):
    for j in range(10001, 0, -1):
        if (dp[j] == True) or ((j >= weights_list[i]) and (dp[j-weights_list[i]] == True)):
            dp[j] = True

if dp[total // 2]:
    print("possible")
else:
    print("impossible")