import sys

N = int(input())
W = list(map(int,input().split()))
W2 = int(sum(W)/2)

if sum(W) % 2 == 1:
    print("impossible")
    sys.exit()

dp = [False] * (W2 + 1)
dp[0] = True
for i in W:
    for j in range(W2, -1, -1):
        if dp[j]:
            if j+i == W2:
                print("possible")
                sys.exit()
            elif j+i < W2:
                dp[j+i] = True

print("impossible")