parameter n=100
	real z(n,n),z1(n,n),z2(n,n)
	open(10,file="line.in")
	open(20,file="line.dat")
	read (10,*)nt,alpha,ik
	
	do i=1,n
	do j=85,n
	z1(i,j)=10.
	z2(i,j)=10.
	enddo
	enddo

c **************** calculation ****************
	do k=1,nt
	
	do i=2,n-1
	do j=2,n-1
	
	if ((j.lt.75.and.j.gt.45).and.(i.gt.55.or.i.lt.45)) then
	z(i,j)=0.
	else
	z(i,j)=2.*z1(i,j)-z2(i,j)+alpha*(z1(i+1,j)+z1(i-1,j)+
     *  z1(i,j+1)+z1(i,j-1)-4.*z1(i,j))
	endif
	
        enddo	
	enddo
	
	do i=1,n
	do j=1,n
	z2(i,j)=z1(i,j)
	z1(i,j)=z(i,j)
	enddo
	enddo

	if((k/ik)*ik.eq.k) then
	write (20,100) z
	endif
	
100	format (100f18.7)
	enddo
	
	stop
	end