Tops at iTunes

The top singles on iTunes for the week ending May 5.

1. "Problem (featuring Iggy Azalea)," Ariana Grande, above

2. "Fancy (featuring Charli XCX)," Iggy Azalea

3. "Happy (From 'Despicable Me 2')," Pharrell Williams

4. "All of Me," John Legend

5. "Turn Down For What," DJ Snake, Lil Jon