PROGRAM conv_obs
	implicit none

	integer, parameter :: NST = 488, SYR = 1980, EYR = 2007, NYR = EYR - SYR + 1, NMN = 12, NDY = 31
	integer :: ist, iyr, imn, idy, itmp, RNDY
	character (len = *), dimension (NMN), parameter :: cmn = (/"01","02","03","04","05","06","07","08","09","10","11","12"/)
	character (len = 100) :: filenm
	character (len = 4) :: cyr, cdy
	real, parameter :: flag = -99.
	real :: rtmp
	real, dimension (NST,NYR,NMN,NDY) :: datain
	real, dimension (NST,NYR,NMN) :: monsum
	real, dimension (NST,NMN) :: yearsum
	! ~~~ --------------------------- ~~~
	! ~~~ BEGIN !!!
	! ~~~ Read Obs_Daily
	monsum = 0.
	datain = flag
 
	do iyr = 1, NYR
	   itmp = SYR + iyr - 1
	   write (cyr,'(i4)') itmp
	   print*, "Reading data in year = ",itmp
	   do imn = 1, NMN
	      RNDY = cnday(itmp,imn)
	      do idy = 1, RNDY
	         if (idy < 10) then
	            write (cdy,'(i1)') idy
	            filenm = "input/OBS_daily/"//trim(cyr)//"/"//trim(cmn(imn))//"/R_day_0"//trim(cdy)//".txt"
	         else
	            write (cdy,'(i2)') idy
	            filenm = "input/OBS_daily/"//trim(cyr)//"/"//trim(cmn(imn))//"/R_day_"//trim(cdy)//".txt"
	         endif
	         open (1,file = filenm,status = "old")
	            do ist = 1, NST
	               read (1,*) rtmp, rtmp, datain(ist,iyr,imn,idy)
	            enddo
	         close (1)
	      enddo
	   enddo
	enddo

	print*,"Calculating sum of Month ... "
	yearsum = 0
	do ist = 1, NST
	   do iyr = 1, NYR
	      do imn = 1, NMN
	         do idy = 1, NDY
	            if (datain(ist,iyr,imn,idy) /= flag) then
	               monsum(ist,iyr,imn) = monsum(ist,iyr,imn) + datain(ist,iyr,imn,idy)
	            endif
	         enddo
	      enddo
	   enddo
	   do imn = 1, NMN
	      do iyr = 1, NYR
	         yearsum(ist,imn) = yearsum(ist,imn) + monsum(ist,iyr,imn)
	      enddo
	      yearsum(ist,imn) = yearsum(ist,imn)/NYR
	   enddo
	enddo

	Print*,"Writing Output ... "
	open(2, file = "output/OBS.txt")
	   do iyr = 1, NYR
	      do imn = 1, NMN
	         do ist = 1, NST
	            write (2,'(F8.3)') monsum(ist,iyr,imn)
	         enddo
	      enddo
	   enddo
	close (2)

	 Print*,"Writing Output ... "
	open(2, file = "output/OBS.yearmean.txt")
	   do ist = 1, NST
	      write (2,'(12(F8.3,2x))') (yearsum(ist,imn),imn = 1, NMN)
	   enddo
	close (2)
	CONTAINS
	! To cal ndays of month.
	integer FUNCTION cnday(year,mon)
	integer :: year, mon
	select case (mon)
	   case (1,3,5,7,8,10,12)
	        cnday = 31
	   case (4,6,9,11)
	        cnday = 30
	   case (2)
	        if (mod(year,4) == 0) then
	           cnday = 29
	           if (mod(year,100) == 0) then
	              if (mod(year,400) /= 0) then
	                 cnday = 28
	              endif
	           endif
	        else
	           cnday = 28
	        endif
	end select
	return
	END FUNCTION
	END
	! ~~~ STOP !!!