"The iCloud Terms of Service have changed."

I bought a new MacBook Air. On startup, It asks me for a password to my iCloud account (I had a MacBook Air previously). After entering my password, I get a red ink message "The iCloud Terms of Service have changed" and I cannot go further. There's no a possibility of accepting the new terms of service. I cannot access the rest of the computer yet; I'm in a startup program window, where you have to go through all the steps to complete the setup, and it doesn't let me skip this. What can I do? Please, help.