program N_data2 
         implicit none
         integer :: N , a, data1
         real*8  :: date2 , sum_N ,  S
         write(*,*) "open file 'date.dat' "
         open (unit=20 ,file='date.dat',status='OLD')
         open (unit=30 ,file='date2.dat',status='REPLACE')
         read(20,*) N
         write(30,*)N 
         write(*,*) "N date, square root date.dat"
         a=1 
         do a = 1 , N
         read(20,*) data1
         date2=data1**(0.5)
         write(30,*) date2
         end do
         close(20)
         close(30)
         write(*,*)"SAVE in 'date2,dat' " 
         stop 
         end program N_data2