import sys
sys.setrecursionlimit(10**6)
n=int(input())
w=list(map(int,input().split()))
mid=-(-sum(w)//2)

dp=[[0]*2*(mid+1) for i in range(n+1)]
dp[-1][0]=1
for i in range(n):
    for ind in range(-mid,mid+1):
        if not dp[i-1][ind]:continue
        if ind+w[i]<=mid:
            dp[i][ind+w[i]]=1
        if -mid<=ind-w[i]:
            dp[i][ind-w[i]]=1

print("possible" if dp[n-1][0] else 'impossible')