import numpy as np

N = int(input())
weights_list = [0] + sorted(list(map(int, input().split(' '))))

total = sum(weights_list)
if total % 2 == 1:
    print("impossible")
    exit()

dp = np.zeros((N + 1, 10001), dtype=np.bool)
dp[0, 0] = True
for i in range(1, N + 1):
    for j in range(10001):
        if (dp[i-1, j] == True) or ((j >= weights_list[i]) and (dp[i-1, j-weights_list[i]] == True)):
            dp[i, j] = True

if dp[-1, total // 2]:
    print("possible")
else:
    print("impossible")