program  gambling
      parameter (w=1000000)
      real e(w)
      print*,"贏、平、輸的賠率分別為："
      read *, a,b,c
      print*,"2元/注，一共投注："
      read *, y
      print *,"一共投注：",y,"投注本金：",2*y
      d=a+b+c
      max=0
      do p=0,y
        do q=0,y-p
            do i=1,w
      x1=2*a*p-2*y
      x2=2*b*q-2*y
      x3=2*(y-p-q)*c-2*y
      e(i)=c/d*x1+b/d*x2+a/d*x3
      if ((e(i).gt.max).and.((y-p-q).gt.0))then
          max=e(i)
          goto 10
          endif
      enddo
      enddo
       
  10    print *,"能賺到錢的期望：",max
          print *,"投贏的注數：",p
          print *,"投平的注數：",q
          print *,"投輸的注數：",y-p-q
      enddo
       end

最近世界杯，本人突發奇想想編寫一個如何投注都不會虧錢的算法，求大神們指點