foo.cc: In function 'int nn(int)':
foo.cc:6:6: warning: statement has no effect [-Wunused-value]
     a/10;
     ~^~~
foo.cc: In function 'int main()':
foo.cc:12:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
     ~~~~~^~~~~~~~~
foo.cc:13:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&num);
     ~~~~~^~~~~~~~~~~

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