import numpy as np

n = int(input())
wl = [int(x) for x in input().split()]

if sum(wl) % 2 == 1:
    print("impossible")
else:

    dp = np.array([[0 for x in range(n * 100 + 1)] for y in range(n + 1)])
    
    for i in range(n + 1):
        dp[i][0] = 1
    
    for i in range(n):
        for j in range(n * 100):
            if dp[i][j] == 1:
                dp[i + 1][j] = 1
                dp[i + 1][j + wl[i]] = 1
    if dp[n][sum(wl) // 2] == 1:
        print("possible")
    else:
        print("impossible")