n = int(input())
W = list(map(int,input().split()))
M = 10**4
dp = [0]*(M+5)

dp[0] = 1
for w in W:
    for i in range(M)[::-1]:
        if dp[i] and i+w <= M:
            dp[i+w] = 1
s = sum(W)
if s%2 == 0 and dp[s//2]:
    print("possible")
else:
    print("impossible")