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

d = [[0 for i in range(10**4 + 1)] for j in range(n+1)]
d[0][0] = 1

s = sum(w)
if s%2 == 1:
    print("impossible")
    exit()
for i in range(n):
    for j in range(10**4 + 1):
        if d[i][j] == 1:
            d[i+1][j] = 1
            d[i+1][j+w[i]] = 1

if d[-1][s//2] == 1:
    print("possible")
else:
    print("impossible")