Six persons namely Raj, Dinesh, Vijay, Aravind, Vivek and Praveen are standing in a queue to get a train ticket in a railway station. Raj is standing between Vivek and Praveen. Praveen is ahead of Dinesh and Vivek is standing behind Aravind. Vijay is standing behind Dinesh. Due to closing time at the ticket counter, they will give tickets only to the first four persons. Who will not get the tickets?