N = int(input())  #おもりの数（２≦Ｎ≦１００）
W = list(map(int,input().split()))  #おもりの重さ（１≦W≦１００）
total = sum(W)

if (total % 2 != 0):
	print("impossible")
else:
	target = total//2
	Judge = [False] * (target + 1)
	Judge[0] = True
	
	for w in W:
		for i in range(target,w-1,-1):
			if (Judge[i-w] == True):
				Judge[i] = True
			else:
				pass
			
	if (Judge[target] == True):
		print("possible")
	else:
		print("impossible")