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