import numpy

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

    su = sum(W)

    if su % 2 == 1:
        print("impossible")
        return

    su = su // 2

    dp = numpy.zeros((N+1, su+1))

    for i in range(N+1):
        dp[i][0] = 1

    for j in range(1, su+1):
        dp[0][j] = 0


    for i in range(1, N+1):
        for j in range(1, su+1):
            w = W[i-1]

            if j-w < 0:
                dp[i][j] = 0
            else:
                dp[i][j] = max(dp[i-1][j], dp[i-1][j-w]) * 1

    if dp[N][su]:
        print("possible")
    else:
        print("impossible")


if __name__ == "__main__":
    main()