program N_data 
         implicit none
         integer :: N , a
!         real*8  :: date ,  S
         write(*,*) "open file 'date.dat' "
         write(*,*) "How many date must input , Please input N "
         read(*,*) N
         open (unit=20 ,file='date.dat',status='REPLACE')
         write(20,*) N
         a=1 
         do a = 1 , N
!         read(*,*) date
         write(20,*) a 
         end do
         close(20)
         write(*,*)"SAVE in 'date,dat' " 
         stop 
         end program N_data