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

Max=max(W)*N+1
dp=[[False]*Max for i in range(N+1)]
dp[0][0]=True

for i in range(N):
    for j in range(Max):
        if j+W[i]<Max:
            dp[i+1][j+W[i]]|=dp[i][j]
        if abs(j-W[i])<Max:
            dp[i+1][abs(j-W[i])]|=dp[i][j]

print("possible" if dp[N][0] else "impossible")