N = int(input())
W = list(map(int,input().split()))
sumW = sum(W)
if sumW%2 != 0:
    print("impossible")
    exit()
half = sumW//2
#dp[i][j]:i番目までの重りを用いて重さjが作れるか
dp = [ [False for _ in range(sumW+1)] for __ in range(N+1)]
for i in range(N):
    dp[i][0] = True
for i in range(N):
    for j in range(sumW):
        dp[i][j] = dp[i-1][j] or dp[i-1][j-W[i]]
for i in range(N):
    if dp[i][half]:
        print("possible")
print("impossible")