module suimin
  TYPE time
     integer::H
     integer::M
  end type time
  TYPE sleep
     type(time)::shuusin
     type(time)::kishou
     integer::sleep_time
  end type sleep
contains
  integer function kaiseki(s,str,N)
    implicit none
    character*16,allocatable::str(:,:)
    type(sleep),allocatable::s(:)
    integer::colon1,colon2,N,i,total=0

    do i=1,N
       colon1 = INDEX(str(1,i),':')
       colon2 = INDEX(str(2,i),':')
       read(str(1,i)(1:colon1-1),*)                  s(i)%shuusin%H
       read(str(1,i)(colon1+1:LEN_TRIM(str(1,i))),*) s(i)%shuusin%M
       read(str(2,i)(1:colon2-1),*)                  s(i)%kishou%H
       read(str(2,i)(colon2+1:LEN_TRIM(str(2,i))),*) s(i)%kishou%M

       s(i)%sleep_time = MOD(((s(i)%kishou%H +24)*60 + s(i)%kishou%M) &
            - ((s(i)%shuusin%H )*60 + s(i)%shuusin%M), 60*24)
       total = total + s(i)%sleep_time
    end do
    kaiseki = total
  end function kaiseki
end module suimin


program main
  use suimin
  integer::N
  character*16,allocatable::str(:,:)
  type(sleep),allocatable::s(:)

  read *,N
  allocate(str(2,N))
  allocate(s(N))
  read *, str

  print '(i0)', kaiseki(s,str,N)

end program main