/in/foo.cc: In function 'int main()':
/in/foo.cc:65:6: warning: 'p' may be used uninitialized in this function [-Wmaybe-uninitialized]
   o[p]++;
   ~~~^
/in/foo.cc:50:6: warning: 'p' may be used uninitialized in this function [-Wmaybe-uninitialized]
   c[p]++;
   ~~~^