n = int(input())
wlst = list(map(int, input().split()))
goal_double = sum(wlst)
if goal_double % 2 == 1:
    print("impossible")
    exit()
goal = goal_double // 2

dp = [False for _ in range(goal + 1)]
dp[0] = True
for w in wlst:
    for i in range(goal, w - 1, -1):
        if dp[i - w]:
            dp[i] = True
if dp[-1]:
    print("possible")
else:
    print("impossible")