fun main(args: Array<String>) {
    nikkei2019QualBB()
}

fun nikkei2019QualBB() {
    val n = readLine()!!.toInt()
    val abc = (1..3).map { readLine()!! }

    val answer = (0 until n).map { i -> abc.map { it[i] }.toSet().size - 1 }.sum()

    println(answer)
}
