program main

 implicit none

 real*8, allocatable :: a(:,:), b(:,:)
 integer, allocatable :: c(:)

 real*8 :: suma, sumb, diag
 integer :: n, l, i, j, k, id

 !1)
 open(10,file='input.dat')
 read(10,*) n,l
 if (l.ge.n) then
   write(*,*) 'n must be greater than l'
   stop
 endif  
 allocate(a(n,l))
 do i=1,n
    read(10,*) (a(i,j), j=1,l)
 enddo 
 close(10)

 !2)
 allocate(b(l,l))
 b(:,:)=a(1:l,:)

 !3)
 suma=0.d0
 do i=l+1,n
    do j=1,l
       suma=suma+a(i,j)
    enddo   
 enddo   

 sumb=0.d0
 do i=1,l 
    do j=1,l,2
       sumb=sumb+b(i,j)
    enddo   
 enddo

 if (suma.ge.sumb) then
    write(*,*) 'Case a', suma, sumb
    diag=0.d0
    do i=1,l
       diag=diag+b(i,i)
    enddo   
    id=abs(int(diag))
    if (id.eq.0) then
       write(*,*) 'Array length equal to zero'
    else   
       allocate(c(id))
       do i=1,id
          c(i)=i+int(a(1,1))
       enddo   
    endif   
 else
    write(*,*) 'Case b', suma, sumb
    id=2*l
    allocate(c(id))
    k=0
    do j=1,2
       do i=1,l
          k=k+1
          c(k)=b(j,i)
       enddo   
    enddo
 endif 

 !4)
 if (id.gt.0) then
    open(10,file='c.dat')
    do i=1,id
       write(10,100) i,c(i)
    enddo   
 endif

 open(11,file='b.dat')
 do i=1,l
    do j=1,l
       write(11,101) i,j,b(i,j)
    enddo
 enddo   
 close(11)

100 format(I5,I5)
101 format(I5,I5,F12.5)

 deallocate(a)
 deallocate(b)
 if (id.gt.0) deallocate(c)

 stop

end program main