.........................
program 20
.........................
      program main
      parameter ( prec = 0.0000001)
      real*8 x_old, x_new, z, f
      integer i,j,k
      read(*,*)z
	x_old = 0
	x_new = 1
	i = 0
	f = 1
	do
          if( abs((x_old-x_new)/x_old) .le. prec)exit
          x_old = x_new
	  i = i + 1
          f = f * i
	  x_new = x_new + z**i/f
	  write(*,*)i,x_new,exp(z)
        enddo
       end

...........................
program 21
...........................
      program main

      real*8 y,sum
      integer i,io

      n = 0
      sum = 0

      do
        read(*,*,IOSTAT=io)y
        if (io .lt. 0) exit
          n = n+1
          sum = sum+y
      enddo

      write(*,*)"number of data= ",n
      write(*,*)"average= ",sum/n
      end

................................
program 22
................................
      program main
      integer x1,x2
      integer n,m,q

      read(*,*)x1
      read(*,*)x2

      if (x1 .ge. x2) then
         n = x1
         m = x2
      else
         n = x2
         m = x1
      endif

      do
        q = mod(n,m)
        if (q .eq. 0) exit
         n = m
         m = q
      enddo

      write(*,*)m
      end