N = int(input())
W = [0]+list(map(int,input().split()))
BASE = N*100
dp = [[0 for _ in range(2*BASE+1)] for _ in range(N+1)]
dp[1][W[1]+BASE] = 1
dp[1][-W[1]+BASE] = 1
for i in range(2,N+1):
    for j in range(-BASE,BASE+1):
        if W[i]+j+BASE<=2*BASE:
            dp[i][j+BASE] = dp[i-1][W[i]+j+BASE]
        if -W[i]+j+BASE>=0:
            dp[i][j+BASE] = max(dp[i][j+BASE],dp[i-1][-W[i]+j+BASE])
if dp[N][BASE]==1:
    print("possible")
else:
    print("impossible")