/in/foo.cc: In function 'int main()':
/in/foo.cc:5:8: warning: unused variable 'b' [-Wunused-variable]
  int a,b,c;
        ^
/in/foo.cc:5:10: warning: unused variable 'c' [-Wunused-variable]
  int a,b,c;
          ^
/in/foo.cc:11:6: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   ans+=1.0/i;
   ~~~^~~~~~~