/in/foo.c: In function 'main':
/in/foo.c:10:12: warning: 'p' may be used uninitialized [-Wmaybe-uninitialized]
   10 |         if (p == 0)
      |            ^
/in/foo.c:4:15: note: 'p' was declared here
    4 |         int n,p;
      |               ^