// https://yukicoder.me/problems/no/2778

fun main() {
    val n: Int = readln().toInt()
    val s = readln()
    for (i in 0..< n) {
        for (j in 0..< n) {
            if (i != j && s[i] == s[j]) {
                println("Yes")
                return

            }

        }
    }
        println("No")
}