foo.cc: In function 'int gy(int, int)':
foo.cc:10:9: warning: 'imax' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return imax;
         ^~~~
foo.cc: In function 'int main()':
foo.cc:6:8: warning: 'imax' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if(n1%i==0&&n2%i==0){
      ~~^~
foo.cc:4:6: note: 'imax' was declared here
  int imax;
      ^~~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。