foo.cc: In function ‘int main()’:
foo.cc:22:19: warning: ‘b’ may be used uninitialized [-Wmaybe-uninitialized]
   22 |         cout<<sum/b;
      |                   ^
foo.cc:8:13: note: ‘b’ was declared here
    8 |         int b,r,a=n;
      |             ^