foo.cc: In function 'int geshu(int*, int)':
foo.cc:34:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(int i=0;i<n;i++)
  ^~~
foo.cc:37:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   return cnt;
   ^~~~~~
foo.cc: In function 'int main()':
foo.cc:9:16: warning: 'n1' is used uninitialized in this function [-Wuninitialized]
  int n1,n2,a[n1],b[n2];
                ^
foo.cc:9:22: warning: 'n2' is used uninitialized in this function [-Wuninitialized]
  int n1,n2,a[n1],b[n2];
                      ^

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