In order to complete the racing competition, the London racetrack has to submit its top and the most famous three horses to win the competition. Due to a electrical storm, all the records are cleared and no one knows which horse holds the record. They all look identical and it becomes even more difficult to differentiate the horses. There are 25 horses in the London racetrack. But there can be only five horses at a time on the track. What will the least number of races that can be conducted to find out the three fastest horses?

The numbers of races are 7.