$\text{ There are five students }{S}_1,S_2,S_3,S_4\text{ and }{S}_5\text{ in a music class and for them there are five seats }{R}_1,R_2,R_3,R_4,$

$\text{ and }{R}_5\text{ arranged in a row, where initially the seat }{R}_i\text{ is allotted to the student }{S}_i,i=1,2,3,4,5.\text{ But, on the }$

$\text{ examination day, the five students are randomly allotted the five seats. }$