n = int(input())
w = list(map(int, input().split()))

sum_w = sum(w)

# dp[i][j] := i番目までの要素を選んだときに、和をjにすることができるかどうか
dp = [[False]*(sum_w+1) for i in range(n+1)]
# 初期値
for i in range(n+1):
    dp[i][0] = True
    
for i in range(n):
    for j in range(sum_w+1):
        if j < w[i]:
            dp[i+1][j] = dp[i][j]
        else:
            dp[i+1][j] = dp[i][j] or dp[i][j-w[i]]
if sum_w % 2 == 1:
    print("impossible")
else:
    if dp[n][sum_w//2]:
        print("possible")
    else:
        print("impossible")