foo.cc: In function 'int main()':
foo.cc:19:28: warning: unused variable 'sg' [-Wunused-variable]
   19 |     long long shu,sum=0,cj,sg;//记得sum初始值赋为0；cj为其中一段运算（即一段连续的乘积）的值
      |                            ^~
foo.cc:29:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   29 |         scanf("%lld",&shu);
      |         ~~~~~^~~~~~~~~~~~~

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