real tv(100,100),tu(100,100),alpha(100,100)
	integer raja(100,100)
	read *, nt
	open (10,file="s_2d_ahi.out")

c******* alg tingimused *********************** 
	tv(:,:)=0.
	tu(:,:)=0.
	
	alpha(:,:)=0.05
	raja(:,:)=0
	do i=40,50
	do j=1,50
	alpha(i,j)=0.00001
	enddo
	enddo
	
!*** aken	
	do i=1,10
	tv(100,i)=0.
	raja(100,i)=1
	enddo

!*** ahi
	do i=1,10
	do j=1,10
	tv(i,j)=100.
	raja(i,j)=1
	enddo
	enddo
	
!*** isoler. seinad
c**********************************************

	do k=1,nt
	 
	do i=1,100
	do j=1,100
	iflag=raja(i,j)
	
	if(iflag.eq.0)then
	sum=alpha(i,j)*
     *  (tv(i+1,j)-4.*tv(i,j)+tv(i-1,j)+tv(i,j+1)+tv(i,j-1))
        tu(i,j)=tv(i,j)+sum
        elseif(iflag.eq.1)then
        tu(i,j)=tv(i,j)
        endif
        
	enddo
	enddo
	
c******  raja tingimused **********************

	do i=10,100
	tu(i,1)=tu(i,2)
	enddo

	do i=1,100
	tu(i,100)=tu(i,99)
	enddo

	do i=10,100
	tu(1,i)=tu(2,i)
	enddo

	do i=10,100
	tu(100,i)=tu(99,i)
	enddo

c***********************************************
	do i=1,100
	do j=1,100
	tv(i,j)=tu(i,j)
	enddo
	enddo	
	
	if((k/10000)*10000.eq.k)then
	write(10,100) tu
100	format(100e15.5)
	endif

	enddo
	
	stop
	end