fun main(args: Array<String>) {
    val n = readInputLine().toInt()
    val s = readInputLine().toMutableList()
    
    var ans = 1L
    
    for (c in 'a'..'z') {
        ans *= (s.count { it == c } + 1L).toLong()
        ans %= 1000000007L
    }
    
    println((ans + 1000000007L - 1L) % 1000000007L)
}

fun readInputLine(): String {
    return readLine()!!
}
