foo.cc: In function 'int main()':
foo.cc:6:10: warning: unused variable 'num' [-Wunused-variable]
    6 |  int a,b,num=0,n=1;
      |          ^~~
foo.cc:7:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    7 |  scanf("%d %d",&a,&b);
      |  ~~~~~^~~~~~~~~~~~~~~

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