rev

f = open('input.txt')
d = {}
for line in f:
    words  = line.strip().split(' - ')
    key = words[0]
    val = words [1].split(',')
    for k in val:
        if k in d:
            d[k].append(key)
        else:
            d[k] = [key]
f.close()
for k in d:
    d[k].sort()
g = open('output.txt', 'w')
g.write(str(len(d)) + '\n')
for val in sorted(d):
    g.write(val + ' - ' + ', '.join(d[val]) + '\n')

g.close()