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

sumW = sum(W)
DP = [False for _ in range(sumW + 1)]

DP[0] = True
for i in range(n):
    for j in range(sumW - W[i], -1, -1):
        DP[j + W[i]] |= DP[j]

if sumW % 2 == 1 or not DP[sumW // 2]:
    print("impossible")
else:
    print("possible")