phillip@Athen:~/script$ perl yanghui.pl
Use of uninitialized value in addition (+) at yanghui.pl line 34.
121
Use of uninitialized value in addition (+) at yanghui.pl line 34.
1331
Use of uninitialized value in addition (+) at yanghui.pl line 34.
14641
Use of uninitialized value in addition (+) at yanghui.pl line 34.
15101051
Use of uninitialized value in addition (+) at yanghui.pl line 34.
1615201561
Use of uninitialized value in addition (+) at yanghui.pl line 34.
172135352171
Use of uninitialized value in addition (+) at yanghui.pl line 34.
18285670562881
Use of uninitialized value in addition (+) at yanghui.pl line 34.
193684126126843691