N = int(input())
W = [int(i) for i in input().split()]

sW = list(reversed(sorted(W)))
target = int(sum(W)/2)
dp ={}
if sum(W)%2 ==0:

    if sW[0] == target: # 最大値がそのままターゲットなら”可能”
        print("possible")
    else:
        for j in range(int(target)+1):
            dp[(N-1,j)] = 0
        for i in reversed(range(N-1)):
            for j in range(int(target)+1):
                if (j < W[i]):
                    dp[(i,j)] = dp[(i+1, j)]
                else:
                    dp[(i,j)] = max(dp[(i+1, j)], dp[(i+1, j - W[i])]+W[i])
        if target == dp[(0,int(target))]:
            print("possible")
        else:
            print("impossible")

else:
    print("impossible")