n=int(input())
arr=list(map(int,input().split()))
add=sum(arr)
div=int(add/2)
flag=(add)%2
dp=[{} for _ in range(n)]
dp[0][arr[0]]=1
for i in range(1,n):
    for j in dp[i-1].keys():
        dp[i][j]=1
        dp[i][j+arr[i]]=1
if flag==1:
    print('impossible')
else:
    if div in dp[n-1]:
        print('possible')
    else:
        print('impossible')