link = []
for i in range(int(input())):
    p = input().split()
    if p[0] == 'insert':
        if p[1] in link:
            index = link.index(p[1])
            link.insert(index,p[2])
        else:
            link.append(p[2])
    elif p[0] == 'delete':
        try:
            link.remove(p[1])
        except:
            pass
if not link:
    print("NULL")
else:
    print(" ".join(link))