/in/foo.cc: In function 'int main()':
/in/foo.cc:13:11: warning: 'i' may be used uninitialized in this function [-Wmaybe-uninitialized]
  for (int i; i<n; i++) cin >> a[i];
           ^
/in/foo.cc:14:11: warning: 'i' may be used uninitialized in this function [-Wmaybe-uninitialized]
  for (int i; i<n-1; i++) a[i]=a[i+1];
           ^