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

c_idx = 10 ** 5
dp = [False] * (2 * c_idx)
dp[c_idx + W[0]] = True
dp[c_idx - W[0]] = True
dp2 = [False] * len(dp)
for i in range(N -1):
    for x in range(2* c_idx):
        if x < W[i+1]:
            dp2[x] = dp[x + W[i+1]]
        elif x + W[i+1] > len(dp) -1:
            dp2[x] = dp[x - W[i+1]]
        else:
            dp2[x] = dp[x + W[i+1]] or dp[x - W[i+1]]
    dp, dp2 = dp2, dp

if dp[c_idx] == True:
    print('possible')
else:
    print('impossible')