import sys

input = sys.stdin.readline


def main():
    N = int(input())
    *W, = map(int, input().split())

    s = sum(W)
    if s % 2 != 0:
        print('impossible')
        return
    
    DP = [False]*(s//2+1)
    DP[0] = True

    for w in W:
        for v in range(s//2, w-1, -1):
            if DP[v-w]: DP[v] = True
    
    print('possible' if DP[-1] else 'impossible')


if __name__ == '__main__':
    main()