/in/foo.cc: In function 'int main()':
/in/foo.cc:27:6: warning: variable 'a2' set but not used [-Wunused-but-set-variable]
  int a2[1000];
      ^~
/in/foo.cc: In function 'int Max(int*, int)':
/in/foo.cc:13:9: warning: 'max' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return max;
         ^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:34:3: warning: 'max' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if(a1[i] == max)
   ^~