n = int(input())
w = list(map(int, input().split()))
wsum = sum(w)
if wsum % 2 != 0:
    print("impossible")
    exit()

wmax = wsum // 2
dp = [[False for i in range(wmax + 1)] for j in range(n + 1)]
dp[0][0] = True

for i in range(1, n+1):
    for j in range(wmax + 1):
        dp[i][j] = dp[i][j] or dp[i-1][j]
        if j >= w[i-1]:
            dp[i][j] = dp[i][j] or dp[i-1][j - w[i-1]]

ans = "possible" if dp[n][wmax] == True else "impossible"
print(ans)