import sys
sys.setrecursionlimit(10**6)
inf=float('inf')

N=int(input())
W=list(map(int,input().split()))
sm=sum(W)

M=101010
dp=[False]*(M+1)
dp[0]=True

for i in range(N):
    for w in range(M,0,-1):
        if W[i]<=w:
            dp[w]=dp[w-W[i]]

print("possible" if sm%2==0 and dp[sm//2] else "impossible")