N = int(input())
A = list(map(int, input().split()))
M = sum(A)
memo = [[False]*(M+1) for _ in range(N+1)]
memo[0][0] = True
for i in range(N):
    for j in range(M+1):
        if memo[i][j] ==False:continue
        memo[i+1][j+A[i]] = True
        memo[i+1][abs(j-A[i])] = True
print('possible' if memo[-1][0] == True else 'impossible')