n = int(input())
weights = list(map(int, input().split()))

half = sum(weights) / 2

dp_set = {0}
for weight in weights:
    new_dp_set = set()
    for dp in dp_set:
        new_dp_set.add(dp + weight)
    dp_set |= new_dp_set
    
    if half in dp_set:
        print('possible')
        break
else:
    print('impossible')