#!python3



import sys

iim = lambda: list(map(int, sys.stdin.readline().rstrip().split()))



def _cmb(N, mod):

    N1 = N + 1

    fact = [1] * N1

    inv = [1] * N1



    for i in range(2, N1):

        fact[i] = fact[i-1] * i % mod



    inv[N] = pow(fact[N], mod-2, mod)

    for i in range(N-1, 1, -1):

        inv[i] = inv[i+1]*(i+1) % mod



    def cmb(a, b):

        return fact[a] * inv[b] * inv[a-b] % mod

    return cmb



def resolve():

    K = int(eval(input()))

    s = eval(input())

    ls = len(s) - 1

    mod = 10**9+7



    cmb = _cmb(ls+K, mod)



    ans = 0

    p25 = 1

    p26 = pow(26, K, mod)

    p26inv = 576923081 #pow(26,  mod-2, mod)

    for i in range(K+1):

        ans = (ans + cmb(ls+i, ls) * p25 * p26) % mod

        p25 = p25 * 25 % mod

        p26 = p26 * p26inv % mod

    print(ans)



if __name__ == "__main__":

    resolve()

#!python3



import sys

iim = lambda: list(map(int, sys.stdin.readline().rstrip().split()))



def _cmb(N, mod):

    N1 = N + 1

    fact = [1] * N1

    inv = [1] * N1



    for i in range(2, N1):

        fact[i] = fact[i-1] * i % mod



    inv[N] = pow(fact[N], mod-2, mod)

    for i in range(N-1, 1, -1):

        inv[i] = inv[i+1]*(i+1) % mod



    def cmb(a, b):

        return fact[a] * inv[b] % mod * inv[a-b] % mod

    return cmb



def resolve():

    K = int(eval(input()))

    s = eval(input())

    ls = len(s) - 1

    mod = 10**9+7



    cmb = _cmb(ls+K, mod)



    ans = 0

    p25 = 1

    p26 = pow(26, K, mod)

    p26inv = 576923081 #pow(26,  mod-2, mod)

    for i in range(K+1):

        ans = (ans + cmb(ls+i, ls) * p25 * p26) % mod

        p25 = p25 * 25 % mod

        p26 = p26 * p26inv % mod

    print(ans)



if __name__ == "__main__":

    resolve()

#!python3
import sys

iim = lambda: list(map(int, sys.stdin.readline().rstrip().split()))


def _cmb(N, mod):
    N1 = N + 1
    fact = [1] * N1
    inv = [1] * N1
    for i in range(2, N1):
        fact[i] = fact[i - 1] * i % mod
    inv[N] = pow(fact[N], mod - 2, mod)
    for i in range(N - 1, 1, -1):
        inv[i] = inv[i + 1] * (i + 1) % mod

    def cmb(a, b):
        return fact[a] * inv[b] * inv[a - b] % mod

    return cmb


def resolve():
    K = int(eval(input()))
    s = eval(input())
    ls = len(s) - 1
    mod = 10**9 + 7
    cmb = _cmb(ls + K, mod)
    ans = 0
    p25 = 1
    p26 = pow(26, K, mod)
    p26inv = 576923081  # pow(26,  mod-2, mod)
    for i in range(K + 1):
        ans = (ans + cmb(ls + i, ls) * p25 * p26) % mod
        p25 = p25 * 25 % mod
        p26 = p26 * p26inv % mod
    print(ans)


if __name__ == "__main__":
    resolve()

#!python3
import sys

iim = lambda: list(map(int, sys.stdin.readline().rstrip().split()))


def _cmb(N, mod):
    N1 = N + 1
    fact = [1] * N1
    inv = [1] * N1
    for i in range(2, N1):
        fact[i] = fact[i - 1] * i % mod
    inv[N] = pow(fact[N], mod - 2, mod)
    for i in range(N - 1, 1, -1):
        inv[i] = inv[i + 1] * (i + 1) % mod

    def cmb(a, b):
        return fact[a] * inv[b] % mod * inv[a - b] % mod

    return cmb


def resolve():
    K = int(eval(input()))
    s = eval(input())
    ls = len(s) - 1
    mod = 10**9 + 7
    cmb = _cmb(ls + K, mod)
    ans = 0
    p25 = 1
    p26 = pow(26, K, mod)
    p26inv = 576923081  # pow(26,  mod-2, mod)
    for i in range(K + 1):
        ans = (ans + cmb(ls + i, ls) * p25 * p26) % mod
        p25 = p25 * 25 % mod
        p26 = p26 * p26inv % mod
    print(ans)


if __name__ == "__main__":
    resolve()

-        return fact[a] * inv[b] * inv[a - b] % mod +        return fact[a] * inv[b] % mod * inv[a - b] % mod