import java.io.BufferedReader
import java.io.InputStreamReader

const val MOD = 1000000007L
val INV_26 = 26L pow -1

fun main() {
    val jin = BufferedReader(InputStreamReader(System.`in`))
    val k = jin.readLine().toInt()
    val n = jin.readLine().length
    var answer = 0L
    var curr = 26L pow k
    for (j in n..n + k) {
        answer += curr
        curr *= (j + 1 - n).toLong() pow -1
        curr %= MOD
        curr *= INV_26
        curr %= MOD
        curr *= j.toLong()
        curr *= 25L
        curr %= MOD
    }
    println(answer % MOD)
}

val MOD_TOTIENT = (MOD - 1).toInt()

infix fun Long.pow(power: Int): Long {
    var e = power
    e %= MOD_TOTIENT
    if (e < 0) {
        e += MOD_TOTIENT
    }
    if (e == 0 && this == 0L) {
        return this
    }
    var b = this % MOD
    var res = 1L
    while (e > 0) {
        if (e and 1 != 0) {
            res *= b
            res %= MOD
        }
        b *= b
        b %= MOD
        e = e shr 1
    }
    return res
}