#scale
N=int(input())
W=[int(i) for i in input().split()]
S=0
for i in range(N):
    S+=W[i]
if S%2==1:
    p="impossible"
else:
    W.sort()
    S//=2
    S-=W[-1]
    W.pop(-1)
    T=[0]
    U=[0]
    for i in range(N):
        T=U
        j=0
        while Nd==0 and j <N:
            v=T[j]+W[i]
            if v==S:
                Nd=1
            else:
                U.append(v)
            set(U)
            j+=1
if Nd==1:
    p="possible"
else:
    p="impossible"
print(p)