foo.cc: In function ‘int rs(int, int, int)’:
foo.cc:24:1: warning: control reaches end of non-void function [-Wreturn-type]
   24 | }
      | ^
foo.cc: In function ‘int yunsuan(int, int, int, int)’:
foo.cc:58:16: warning: ‘ret’ may be used uninitialized [-Wmaybe-uninitialized]
   58 |         return ret;
      |                ^~~
foo.cc:27:13: note: ‘ret’ was declared here
   27 |         int ret,ax,bx;
      |             ^~~