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

sumW = sum(W)

if sumW & 1:
    print("impossible")
    exit()

s2 = sumW //2
dp = [False] * (s2 + 1)
dp[0] = True

for w in W:
    for i in range(s2+1)[::-1]:
        if i-w < 0:
            break
        dp[i] |= dp[i-w]

print("possible" if dp[s2] else "impossible")