/in/foo.cc: In function 'int main()':
/in/foo.cc:21:7: warning: 'b' may be used uninitialized [-Wmaybe-uninitialized]
   21 | cout<<b;
      |       ^
/in/foo.cc:8:9: note: 'b' was declared here
    8 | int a=n,b,r;
      |         ^