from copy import copy
n=int(input())
w=list(map(int,input().split()))
hw=int(sum(w)/2)
if hw*2!=sum(w):
    print("impossible")
else:
    table=[0 for i in range(hw+1)]
    table[0]=1
    for i in w:
        ntable=copy(table)
        for j in range(hw+1):
            try:
                ntable[j+i]=max(table[j+i],table[j])
            except:
                pass
        table=copy(ntable)
    if table[-1]==1:
       print("possible")
    else:
       print("impossible")