real U2(300,300), U1(300,300), U0(300,300)
      integer rt(300,300)
!      open (10, file="laine.in")
      open (20,file="laine.out")
      read *,nt
      alpha=0.05

!***** alg tingimused *****
      do i=1,300
      do j=1,300
      U1(i,j)=0.
      U0(i,j)=0.
      rt(i,j)=1
      enddo
      enddo
      
      do i=1,5
      do j=2,299
      U1(i,j)=10.
      U0(i,j)=10.
      enddo
      enddo
      
      do i=45,55
      do j=175,300
      rt(i,j)=0
      enddo
      enddo
      do i=45,55
      do j=135,165
      rt(i,j)=0
      enddo
      enddo
      do i=45,55
      do j=1,125      
      rt(i,j)=0
      enddo
      enddo
!**********************************************
      do k=1,nt
      
      do i=2,299
      do j=2,299
      if(rt(i,j).eq.1)then 
      U2(i,j)=alpha*(U1(i+1,j)-4.*U1(i,j)+U1(i-1,j)
     *+U1(i,j+1)+U1(i,j-1))+2.*U1(i,j)-U0(i,j)
      endif
      enddo
      enddo
!****** raja tingimused *********
      do i=1,300
      U2(i,300)=0.
      U2(i,1)=0.
      U2(300,i)=0.
      U2(1,i)=0.
      enddo
      
!****** salvestamine ***************
      do i=1,300
      do j=1,300
      U0(i,j)=U1(i,j)
      U1(i,j)=U2(i,j)
      enddo
      enddo
!****** kirjutamine ********
      if((k/5)*5.eq.k)then
      write(20,100) U2
100   Format (300F12.5)
      endif
      enddo
!***********************************************
      stop
      end