Burger King’s “Whopper Detour,” which directed McDonald’s customers to the nearest Burger King with the promise of a sandwich for a penny, won the Direct Grand Prix at the Cannes Lions International Festival of Creativity, as well as two Gold Lions in the category.

Made by FCB New York, the campaign rebooted Burger King’s mobile app. The agency geofenced all 14,000 McDonald’s locations in the U.S. When app users came within 600 feet of a McDonald’s, they were served an offer for a Whopper for 1 cent, provided that they traveled to the nearest Burger King to get it. Of course, the app provided convenient directions.

That wasn’t a big ask of users since there’s almost always a McDonald’s within a mile of all 7,200 Burger King locations in the country, FCB New York Executive Creative Director Gabriel Schmitt told Ad Age.

The jury, led by Nicky Bullard, chairwoman and chief creative officer at MRM//McCann, considered four questions for each piece of work: Was the work targeted? Have you made me feel something? Have you asked me to do something? Can you prove I did it? Using those criteria, the jury was unanimous in its decision to choose “Whopper Detour.”

“It was just pure genius,” Bullard said. “It was a complete, direct campaign. It used data and targeting, absolutely did it make you feel something. Yes, it asked you to do something and millions of people did it, but it was actually answering a business problem.”

It was that last point that helped push “Whopper Detour” above the competition, which included Ikea’s “ThisABLES,” the winner of the Health and Wellness Grand Prix. “There are some brands that have done work for good, which has been wonderful,” Bullard says. “But the work that won was absolutely relevant to their brand. It wasn’t just a nice-to-do.”