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

w=int(sum(W)/2)

def ans():
    if sum(W)%2!=0:
        return 0
    a=[[0]*(w+1) for i in range(N+1)]
    a[0][0]=1
    for i in range(1,N+1):
        for j in range(w+1):
            if j>=W[i-1]:
                if a[i-1][j-W[i-1]]==1:
                    a[i][j]=1
            if a[i-1][j]==1:
                a[i][j]=1
    return a[N][w]

def c(n):
    if n==1:
        return 'possible'
    if n==0:
        return 'impossible'

print(c(ans()))