N = int(input())
W = list(map(int,input().split(" ")))
sum = 0
for i in range(N):
    sum += W[i]
if sum % 2 != 0:
    print("impossible")
    exit()
dp = [[False for _ in  range(sum + 1)]for __ in range(N+1)]


for i in range(N):
    dp[i][0] = True
for i in range(1,N):
    for j in range(1,sum):
        dp[i][j] = dp[i-1][j] or dp[i-1][j-W[i]] 

  
for i in range(N):
    if dp[i][int(sum/2)]:
        print("possible")
        exit()
    
print("impossible")