n=int(input())
w=list(map(int,input().split()))
if sum(w)%2!=0:
    print("impossible")
else:
    total=int(sum(w)/2)
    dp=[False]*(total+1)
    dp[0]=True

    for i in w:
        for j in reversed(range(i-1,total+1)):
            dp[j] |= dp[j-i]
    if dp[total]:
        print("possible")
    else:
        print("impossible")