import java.util.*

fun main() {
    q2675()
}

fun q2675() = with(Scanner(System.`in`)) {
    val inputs = List(nextInt()) { Pair(nextInt(), next().toCharArray()) }

    for(input in inputs) {
        val sb = StringBuilder(input.second.count() * input.first)
        for(char in input.second) {
            for (i in 1..input.first) {
                sb.append(char)
            }
        }
        println(sb)
    }
}