Six friends Sheela, Roma, Sheetal, Sreeja, Naina and Rahul are sitting on a bench facing north. Sreeja and Rahul are sitting at the 3^rd and 4^th positions respectively from the left end. Sheela and Naina are sitting at the extreme right and left ends, respectively. Sheela is sitting to the immediate right of Roma. Who is sitting immediately next to Naina?