# coding: utf-8

iin = int(raw_input())
iiw = map(int, raw_input().split())

Max = 100*100

dp = [False]*(Max+1)
dp[0] = True
sum = 0

for x in iiw:
    sum += x
    for i in xrange(Max, -1, -1):
	    if dp[i] : dp[i+x] = True

if ((sum%2==0) and dp[sum/2]) : 
    print "possible"
else : 
    print "impossible"