foo.cc: In function ‘int main()’:
foo.cc:21:17: warning: ‘b’ may be used uninitialized [-Wmaybe-uninitialized]
   21 |         cout<<x/b;
      |                 ^
foo.cc:7:13: note: ‘b’ was declared here
    7 |         int b,r,a=n,x=n;
      |             ^