123192020
12345 67891 01112 13141 51617 18192 0
3120
2011()
199812345678129101112131415161
95617181920
2080
123798080
123456789101112…787980
80
1998
1019919
20293039919
8+19+19+19=65
80-65=15
40491574849
9999748495051…787980