Office 365 domain

Hi,
We are evaluating office 365 for our official use for our communications needs. Let me explain our scenario first,
actually we are the multinational company, our head office is based out side our country, the emails of all
the head office users and our office users are hosted at our head office Exchange Server with the same email
domain policy for all users ie user@company.com. Now we want to migrate only our country users to office 365, and also we don't want to change our emails domain ie user@company.com. My question is that can we migrate to office 365 without changing our email addresses ie user@comapny.com?because our head office will also be using that user@company.com domain in their under premises Exchange