f = open('input.txt')
f_out = open('output.txt', 'w')
d = []
for line in f:
    if (line[1:3] in d) or ((d == []) and (line[0] == '/')) or ((d == []) and (line[0] == '^')):
        f_out.write('ERROR')
        exit()
    if (line[0] == '+'):
        d.insert(0, line[1:3])
    elif (line[0] == '#'):
        d.append(line[1:3])
    elif (line[0] == '^'):
        d.pop(0)
    elif (line[0] == '/'):
        d.pop()
if (not d):
    f_out.write('EMPTY')
else:
    f_out.write(' '.join(d))
f.close()
f_out.close()