N = int(input())
W = list(map(int, input().split()))

A = sum(W)

if (A/2).is_integer() == False:
    print('impossible')
    exit()
else:
    A = int(A/2)
    S = [[0]*(A+1)]*(N+1)
    S[0][0] = 1
    for i in range(N):
        for j in range(A+1):
            if S[i][j] == 1:
                if j + W[i] > A:
                    A = A+0  
                else:
                    S[i+1][j+W[i]] = 1
                    S[i+1][j] = 1
    if S[N-1][A] == 1:
        print('possible')
    else:
        print('impossible')