n, m = raw_input().split()
p = []
for i in xrange(int(n)):
tokens = raw_input().split()
p.append( (tokens[0], sum(int(scr) for scr in tokens[1:])/float(m)) )
print '%.2f' % ( reduce(lambda x,y: x+y[1], p, 0)/float(n) )
for student in p:
print '%s %.2f' % (student[0], student[1])
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