IMPLICIT NONE
      REAL*8 ran, a, e, p, w, g
      INTEGER i, iseed, ntrial, j, k, s(0:32, 0:32), m, l
      write(6,*) 'n?' 
        read(5,*) ntrial
      w=1.5
      iseed=106
      open(unit = 10, file = '80.prn',
     $  form = 'formatted')
      m = 961
      do 20 i=0,32
       do 10 j=0,32
       s(i, j) = 1
   10  continue
   20 continue
   
      do 40 l=1,ntrial
       do 30 k=1,962
       i=int(ran(iseed)*31.0)+1.0
       j=int(ran(iseed)*31.0)+1.0
       e=-s(i, j)*(s(i, j-1)+s(i, j+1)+s(i-1, j)+s(i+1, j))
       if (e.ge.0) goto 23
       p=exp(e/w)
       a=ran(iseed)
       if (p.lt.a) goto 25
   23  continue
       s(i, j)=-s(i, j)
       m=m+s(i, j)
       s(32, j)=s(1, j)
       s(0, j)=s(31, j)
       s(i, 32)=s(i, 0)
       s(i, 0)=s(i, 31)
       s(32, 32)=s(1, 1)
       s(32, 0)=s(1, 31)
       s(0, 0)=s(31, 31)
       s(0, 32)=s(31, 1)
   25  continue
   30  continue
      g=(2*(m/(961.0))-1.0)
      write(6,*) l, '    ', g, '    ', m
      g = 0
   40 continue

      do 60 i=0,32
       do 50 j=0,32
       write(10,*) s(i, j)
   50  continue
       write(10,*) '     '
       write(10,*) '     '
       write(10,*) '     '
   60 continue
 9999   stop
      end

        function ran(iseed)
        iseed=iseed*48828125
        if(iseed.le.0) iseed=(iseed+2147483647)+1
        ran=float(iseed)/2147483647
        return
        end