import sys
N = int(input())
W = list(map(int, input().split()))
sum = 0
for i in range(len(W)):
    sum += W[i]

#合計が偶数でない時に終了
if sum % 2 != 0:
    print("impossible")
    sys.exit()
    
hsum = int(sum / 2)

DP = [[0 for i in range(hsum + 1)] for j in range(N + 1)]
DP[0][0] = 1
for i in range(1, N + 1):
    for j in range(0, hsum + 1):
        if j < W[i-1]:
            DP[i][j] = DP[i-1][j]
        else:
            if DP[i-1][j-W[i-1]] == 1:
                DP[i][j] = 1
            elif DP[i-1][j] == 1:
                DP[i][j] = 1

if DP[N][hsum] == 1:
    print("possible")
else:
    print("impossible")