PROGRAM ATCODER

implicit none
integer :: n,i,s
character(len=100) :: a,b,c

read(*,*) n,a,b,c    !ここが入力欄

s = 0
do i = 1,n
if (a(i:i) /= b(i:i) .or. a(i:i) /= c(i:i))then
    s = s + 2
    if (a(i:i) == b(i:i) .or. b(i:i) == c(i:i) .or. c(i:i) == a(i:i))then
        s = s - 1
    end if
end if
end do

write(*,'(i0)') s

END PROGRAM ATCODER