n = int(input())
w_list = list(map(int,input().split()))
all_weight = sum(w_list)
if all_weight%2==1:
    print("impossible")
else:
    target = all_weight//2
    dp = [[False for i in range(target)] for i in range(n+1)]
    for i in range(1,n+1):
        for j in range(target):
            if (j >= w_list[i] and dp[i][j - w_list[i]] == True) or dp[i][j] == True:
                dp[i+1][j] = True
            else:
                dp[i+1][j] = False
                
    if dp[-1][target] == True:
        print("possible")
    else:
        print("impossible")