program main
implicit none
integer,parameter :: students
integer,parametrt :: classes
integer :: student(students,classes)
integer s
integer c
do c=1,classes
do s=1,students
write(*,"('Number',I2,' of class ',I2") s,c
read(*,*)student(s,c)
end do
end do
do while(.true.)
write(*,*) "class:"
read(*,*)c
if(c<=0 .or. c>classes)exit
write(*,*)"student:"
read(*,*)s
if(c<=0 .or. s>students)exit
write(*,"(student)",I3)student(s,c)
end do
stop
end