n = int(input())
w = list(map(int, input().split(" ")))
s = sum(w)
if s % 2 == 1:
    print("impossible")
    exit()
s //= 2
t = [[0]*(s+1) for _ in range(n+1)]
t[0][0] = 1
for i in range(n):
    for j in range(s+1):
        if t[i][j] == 1:
            t[i+1][j] = 1
            if j + w[i] <= s:
                t[i+1][j+w[i]] = 1
if t[n][s] == 1:
    print("possible")
else:
    print("impossible")