foo.cc: In function 'int add_char(int, int)':
foo.cc:47:1: warning: no return statement in function returning non-void [-Wreturn-type]
   47 | }
      | ^
foo.cc: In function 'int main()':
foo.cc:76:14: warning: format '%d' expects argument of type 'int', but argument 2 has type 'll' {aka 'long long int'} [-Wformat=]
   76 | printf( "%I64d\n" , ans ) ;
      |          ~~~~^      ~~~
      |              |      |
      |              int    ll {aka long long int}
      |          %I64lld
foo.cc:70:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   70 | scanf( "%d" , &n ) ;
      | ~~~~~^~~~~~~~~~~~~

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