n=int(input()) W=list(map(int,input().split())) if sum(W)%2!=0: print('impossible') exit() dp=[[False]*(100*100) for _ in range(n+1)] dp[0][0]=True for i in range(n): for j in range(100*100): if dp[i][j]==True: dp[i+1][j+W[i]]=True dp[i+1][j]=True for i in range(n): if dp[i][sum(W)//2]==True: print('possible') exit() else: print('impossible')