When to call NRJ for the double hit?

Hello, I want to try my luck on NRJ to win a ticket to Euro 2016 at Champ de Mars, but I need to call between the two hits. For those in the know, do you know what the other hit by Guetta is after "This One's for You"? And when exactly do we have the best chances to call, like in the middle of the first hit? At the very end of the first one? Do I need to call before it finishes? Thanks!

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