def dfs(i,Sum,N,W,sumW,found):
	if found >= 1:return found
	if Sum > sumW / 2:return found
	if i == N and Sum == sumW / 2:
		found += 1
		return found
	if i >= N:return found
	found += dfs(i + 1,Sum + W[i],N,W,sumW,found)
	found += dfs(i + 1,Sum,N,W,sumW,found)
	return found
if  __name__ == '__main__':
	N = int(raw_input())
	W = map(int,raw_input().split())
	if sum(W) % 2 == 0:
		if dfs(0,0,N,W,sum(W),0) >= 1:
			print 'possible'
		else:
			print 'impossible'
	else:
		print 'impossible'