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 j in range(wmax + 1)] dp[0] = True for i in range(1, n+1): for j in range(wmax + 1): if j >= w[i-1]: dp[j] = dp[j] or dp[j - w[i-1]] ans = "possible" if dp[wmax] == True else "impossible" print(ans)