/in/foo.cc: In function 'int main()':
/in/foo.cc:6:11: warning: unused variable 'a' [-Wunused-variable]
   int n,i,a[i];
           ^
/in/foo.cc:6:14: warning: 'i' is used uninitialized in this function [-Wuninitialized]
   int n,i,a[i];
              ^