foo.cc: In function 'int gcd(int, int)':
foo.cc:10:1: warning: control reaches end of non-void function [-Wreturn-type]
   10 | }
      | ^
foo.cc: In function 'int main()':
foo.cc:15:27: warning: 'z' may be used uninitialized in this function [-Wmaybe-uninitialized]
   15 |  int len = x.length(), y, z,
      |                           ^
foo.cc:15:24: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized]
   15 |  int len = x.length(), y, z,
      |                        ^

[Hydro](https://hydro.ac)提供评测服务