#おもりと天秤

N = 0
W = []
total = 0

def sumup(s , sum):
    if s > N // 2 and sum == 0:
        return False
    else:
        for i in range(s , N):
            sum += W[i]
            if sum == total:
                return True
            elif sum < total:
                if i + 1 < N:
                    if sumup(i + 1 , sum):
                        return True
                    else:
                        sum -= W[i]
                        return sumup(i + 1 , sum)
                else:
                    return False
            
            

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

for i in W:
    total += i

W.sort()

if total % 2 == 1:
    print("impossible")
else:
    total = total // 2
    if sumup(0 , 0):
        print("possible")
    else:
        print("impossible")