N = int(input()) W = list(map(int, input().split())) total = sum(W) if total % 2: print('impossible') else: half = total // 2 dp = [0] * (half + 1) dp[0] = 1 for w in W: for i in range(half, w - 1, -1): if dp[i - w]: dp[i] = 1 if dp[half]: print('possible') break print('impossible')