fun main() {
    val i = readLine()!!.toInt()
    val cheater = LinkedHashMap<String, String>(i)
    repeat(i) {
        val (c, d) = readLine()!!.split(" ")
        cheater[c] = d
    }
    
    cheater.values.forEach { 
        // 被害者
        if (cheater[it] == null) {
            println(it)
        }
    }
}