import sys
N = int(input())
lsW = list(map(int,input().split()))
sum1 = sum(lsW)
if sum1%2 == 1:
    print('impossible')
    sys.exit()
dp = [[False]*(10000+1) for i in range(N+1)]
dp[0][0] = True
for i in range(N):
    for j in range(10000+1):
        if j - lsW[i] < 0:
            dp[i+1][j] = dp[i][j]
        else:
            dp[i+1][j] = (dp[i][j] or dp[i][j-lsW[i]])
print('possible' if dp[N][sum1//2] else 'impossible')