Counting Loop দিয়ে গড় ও Standard Deviation নির্ণয়

program sdcnt
implicit none
real::i,sd,a,x=0,sumx=0,sumx2=0
integer::n=0
write(*,*)'wnter no. of points'
read(*,*)n
if (n<2) then
  write(*,*)'minimum 2 values needed'
  else
    do i=1,n
      write(*,*)'enter number'
      read(*,*)x
      write(*,*)'the no. is',x
      sumx=sumx+x
      sumx2=sumx2+x**2
      enddo
      a=sumx/real(n)
      sd=sqrt((real(n)*sumx2-sumx**2)/(real(n)*real(n-1)))
      write(*,*)'mean=',a,'SD=',sd,'n=',n
      endif
      endprogram sdcnt