foo.cc: In function 'int main()':
foo.cc:17:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
foo.cc:18:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   18 |  scanf("%d",&a);
      |  ~~~~~^~~~~~~~~
foo.cc:22:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   22 |   scanf("%d",&a);
      |   ~~~~~^~~~~~~~~
foo.cc:40:8: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   40 |  cout<<ans;
      |        ^~~

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