N = int(input())
W = list(map(int,input().split(" ")))
sum = 0
dp = [[0]*10001]*101
dp[0][0] = True
for i in range(N):
    sum += W[i]
if sum % 2 == 1:
    print("impossible")
else:
    for i in range(N):
        for j in range(sum):
            if dp[i][j] == True:
                dp[i + 1][j+W[i]] = True
                dp[i+1][j] = True


  
    if dp[N][int(sum/2)]==True:
        print("possible")
    else:
        print("impossible")