import sys

import numpy as np

from numba import njit



read = sys.stdin.buffer.read

readline = sys.stdin.buffer.readline

readlines = sys.stdin.buffer.readlines



MOD = 10**9 + 7



def main(K, N, MOD):

    def fact_table(N, MOD):

        inv = np.empty(N, np.int64)

        inv[0] = 0

        inv[1] = 1

        for n in range(2, N):

            q, r = divmod(MOD, n)

            inv[n] = inv[r] * (-q) % MOD

        fact = np.empty(N, np.int64)

        fact[0] = 1

        for n in range(1, N):

            fact[n] = n * fact[n - 1] % MOD

        fact_inv = np.empty(N, np.int64)

        fact_inv[0] = 1

        for n in range(1, N):

            fact_inv[n] = fact_inv[n - 1] * inv[n] % MOD

        return fact, fact_inv, inv



    fact, fact_inv, inv = fact_table(3_000_000, MOD)

    f = np.zeros(K + 1, np.int64)

    f = fact[N - 1:K + N] * fact_inv[N - 1] % MOD * fact_inv[0:K + 1] % MOD

    x = 1

    for i in range(1, K + 1):

        x = (x * 25) % MOD

        f[i] = f[i] * x % MOD

    for i in range(1, K + 1):

        f[i] += f[i - 1] * 26

        f[i] %= MOD

    return f[-1]



if sys.argv[-1] == 'ONLINE_JUDGE':

    import numba

    from numba.pycc import CC

    i8 = numba.from_dtype(np.int64)

    signature = (i8, i8, i8)



    cc = CC('my_module')

    cc.export('main', signature)(main)

    cc.compile()



from my_module import main



K = int(readline())

N = len(read().rstrip())



print((main(K, N, MOD)))
import sys

import numpy as np



read = sys.stdin.buffer.read

readline = sys.stdin.buffer.readline

readlines = sys.stdin.buffer.readlines



MOD = 10**9 + 7



def main(K, N, MOD):

    def fact_table(N, MOD):

        inv = np.empty(N, np.int64)

        inv[0] = 0

        inv[1] = 1

        for n in range(2, N):

            q, r = divmod(MOD, n)

            inv[n] = inv[r] * (-q) % MOD

        fact = np.empty(N, np.int64)

        fact[0] = 1

        for n in range(1, N):

            fact[n] = n * fact[n - 1] % MOD

        fact_inv = np.empty(N, np.int64)

        fact_inv[0] = 1

        for n in range(1, N):

            fact_inv[n] = fact_inv[n - 1] * inv[n] % MOD

        return fact, fact_inv, inv



    fact, fact_inv, inv = fact_table(3_000_000, MOD)

    f = np.zeros(K + 1, np.int64)

    f = fact[N - 1:K + N] * fact_inv[N - 1] % MOD * fact_inv[0:K + 1] % MOD

    x = 1

    for i in range(1, K + 1):

        x = (x * 25) % MOD

        f[i] = f[i] * x % MOD

    for i in range(1, K + 1):

        f[i] += f[i - 1] * 26

        f[i] %= MOD

    return f[-1]



if sys.argv[-1] == 'ONLINE_JUDGE':

    import numba

    from numba.pycc import CC

    i8 = numba.from_dtype(np.int64)

    signature = (i8, i8, i8)



    cc = CC('my_module')

    cc.export('main', signature)(main)

    cc.compile()



from my_module import main



K = int(readline())

N = len(read().rstrip())



print((main(K, N, MOD)))
import sys
import numpy as np
from numba import njit

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
MOD = 10**9 + 7


def main(K, N, MOD):
    def fact_table(N, MOD):
        inv = np.empty(N, np.int64)
        inv[0] = 0
        inv[1] = 1
        for n in range(2, N):
            q, r = divmod(MOD, n)
            inv[n] = inv[r] * (-q) % MOD
        fact = np.empty(N, np.int64)
        fact[0] = 1
        for n in range(1, N):
            fact[n] = n * fact[n - 1] % MOD
        fact_inv = np.empty(N, np.int64)
        fact_inv[0] = 1
        for n in range(1, N):
            fact_inv[n] = fact_inv[n - 1] * inv[n] % MOD
        return fact, fact_inv, inv

    fact, fact_inv, inv = fact_table(3_000_000, MOD)
    f = np.zeros(K + 1, np.int64)
    f = fact[N - 1 : K + N] * fact_inv[N - 1] % MOD * fact_inv[0 : K + 1] % MOD
    x = 1
    for i in range(1, K + 1):
        x = (x * 25) % MOD
        f[i] = f[i] * x % MOD
    for i in range(1, K + 1):
        f[i] += f[i - 1] * 26
        f[i] %= MOD
    return f[-1]


if sys.argv[-1] == "ONLINE_JUDGE":
    import numba
    from numba.pycc import CC

    i8 = numba.from_dtype(np.int64)
    signature = (i8, i8, i8)
    cc = CC("my_module")
    cc.export("main", signature)(main)
    cc.compile()
from my_module import main

K = int(readline())
N = len(read().rstrip())
print((main(K, N, MOD)))

import sys
import numpy as np

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
MOD = 10**9 + 7


def main(K, N, MOD):
    def fact_table(N, MOD):
        inv = np.empty(N, np.int64)
        inv[0] = 0
        inv[1] = 1
        for n in range(2, N):
            q, r = divmod(MOD, n)
            inv[n] = inv[r] * (-q) % MOD
        fact = np.empty(N, np.int64)
        fact[0] = 1
        for n in range(1, N):
            fact[n] = n * fact[n - 1] % MOD
        fact_inv = np.empty(N, np.int64)
        fact_inv[0] = 1
        for n in range(1, N):
            fact_inv[n] = fact_inv[n - 1] * inv[n] % MOD
        return fact, fact_inv, inv

    fact, fact_inv, inv = fact_table(3_000_000, MOD)
    f = np.zeros(K + 1, np.int64)
    f = fact[N - 1 : K + N] * fact_inv[N - 1] % MOD * fact_inv[0 : K + 1] % MOD
    x = 1
    for i in range(1, K + 1):
        x = (x * 25) % MOD
        f[i] = f[i] * x % MOD
    for i in range(1, K + 1):
        f[i] += f[i - 1] * 26
        f[i] %= MOD
    return f[-1]


if sys.argv[-1] == "ONLINE_JUDGE":
    import numba
    from numba.pycc import CC

    i8 = numba.from_dtype(np.int64)
    signature = (i8, i8, i8)
    cc = CC("my_module")
    cc.export("main", signature)(main)
    cc.compile()
from my_module import main

K = int(readline())
N = len(read().rstrip())
print((main(K, N, MOD)))

-from numba import njit