#標準入力　テスト

import sys

input = lambda: sys.stdin.readline().rstrip()

K=int(eval(input()))

S=eval(input())

M=len(S)

N=K+M

mod=10**9+7

ans=pow(26,N,mod)

class Data():

    def __init__(self):

        self.power=1

        self.rev=1     

class Combi():

    def __init__(self,N,mod):

        self.lists=[Data() for _ in range(N+1)]

        self.mod=mod  

        for i in range(2,N+1):

            self.lists[i].power=((self.lists[i-1].power)*i)%self.mod

        self.lists[N].rev=pow(self.lists[N].power,self.mod-2,self.mod)

        for j in range(N,0,-1):

            self.lists[j-1].rev=((self.lists[j].rev)*j)%self.mod



    def combi(self,K,R):

        if K<R:

            return 0

        else:

            return ((self.lists[K].power)*(self.lists[K-R].rev)*(self.lists[R].rev))%self.mod

        

c=Combi(2*10**6,mod)

for i in range(M):

    ans-=c.combi(N,i)*pow(25,N-i,mod)

    ans%=mod

print(ans)

# ライブラリ高速化実験テスト

import sys





class Combi():

    def __init__(self, N, mod):

        self.power = [1 for _ in range(N+1)]

        self.rev = [1 for _ in range(N+1)]

        self.mod = mod

        for i in range(2, N+1):

            self.power[i] = (self.power[i-1]*i) % self.mod

        self.rev[N] = pow(self.power[N], self.mod-2, self.mod)

        for j in range(N, 0, -1):

            self.rev[j-1] = (self.rev[j]*j) % self.mod



    def com(self, K, R):

        if K < R:

            return 0

        else:

            return ((self.power[K])*(self.rev[K-R])*(self.rev[R])) % self.mod



    def pom(self, K, R):

        if K < R:

            return 0

        else:

            return (self.power[K])*(self.rev[K-R]) % self.mod







def input(): return sys.stdin.readline().rstrip()





K = int(eval(input()))

S = eval(input())

M = len(S)

N = K+M

mod = 10**9+7

ans = pow(26, N, mod)



c = Combi(2*10**6, mod)

for i in range(M):

    ans -= c.com(N, i)*pow(25, N-i, mod)

    ans %= mod

print(ans)
# 標準入力　テスト
import sys

input = lambda: sys.stdin.readline().rstrip()
K = int(eval(input()))
S = eval(input())
M = len(S)
N = K + M
mod = 10**9 + 7
ans = pow(26, N, mod)


class Data:
    def __init__(self):
        self.power = 1
        self.rev = 1


class Combi:
    def __init__(self, N, mod):
        self.lists = [Data() for _ in range(N + 1)]
        self.mod = mod
        for i in range(2, N + 1):
            self.lists[i].power = ((self.lists[i - 1].power) * i) % self.mod
        self.lists[N].rev = pow(self.lists[N].power, self.mod - 2, self.mod)
        for j in range(N, 0, -1):
            self.lists[j - 1].rev = ((self.lists[j].rev) * j) % self.mod

    def combi(self, K, R):
        if K < R:
            return 0
        else:
            return (
                (self.lists[K].power) * (self.lists[K - R].rev) * (self.lists[R].rev)
            ) % self.mod


c = Combi(2 * 10**6, mod)
for i in range(M):
    ans -= c.combi(N, i) * pow(25, N - i, mod)
    ans %= mod
print(ans)

# ライブラリ高速化実験テスト
import sys


class Combi:
    def __init__(self, N, mod):
        self.power = [1 for _ in range(N + 1)]
        self.rev = [1 for _ in range(N + 1)]
        self.mod = mod
        for i in range(2, N + 1):
            self.power[i] = (self.power[i - 1] * i) % self.mod
        self.rev[N] = pow(self.power[N], self.mod - 2, self.mod)
        for j in range(N, 0, -1):
            self.rev[j - 1] = (self.rev[j] * j) % self.mod

    def com(self, K, R):
        if K < R:
            return 0
        else:
            return ((self.power[K]) * (self.rev[K - R]) * (self.rev[R])) % self.mod

    def pom(self, K, R):
        if K < R:
            return 0
        else:
            return (self.power[K]) * (self.rev[K - R]) % self.mod


def input():
    return sys.stdin.readline().rstrip()


K = int(eval(input()))
S = eval(input())
M = len(S)
N = K + M
mod = 10**9 + 7
ans = pow(26, N, mod)
c = Combi(2 * 10**6, mod)
for i in range(M):
    ans -= c.com(N, i) * pow(25, N - i, mod)
    ans %= mod
print(ans)

-# 標準入力　テスト +# ライブラリ高速化実験テスト -input = lambda: sys.stdin.readline().rstrip() + +class Combi: +    def __init__(self, N, mod): +        self.power = [1 for _ in range(N + 1)] +        self.rev = [1 for _ in range(N + 1)] +        self.mod = mod +        for i in range(2, N + 1): +            self.power[i] = (self.power[i - 1] * i) % self.mod +        self.rev[N] = pow(self.power[N], self.mod - 2, self.mod) +        for j in range(N, 0, -1): +            self.rev[j - 1] = (self.rev[j] * j) % self.mod + +    def com(self, K, R): +        if K < R: +            return 0 +        else: +            return ((self.power[K]) * (self.rev[K - R]) * (self.rev[R])) % self.mod + +    def pom(self, K, R): +        if K < R: +            return 0 +        else: +            return (self.power[K]) * (self.rev[K - R]) % self.mod + + +def input(): +    return sys.stdin.readline().rstrip() + + - - -class Data: -    def __init__(self): -        self.power = 1 -        self.rev = 1 - - -class Combi: -    def __init__(self, N, mod): -        self.lists = [Data() for _ in range(N + 1)] -        self.mod = mod -        for i in range(2, N + 1): -            self.lists[i].power = ((self.lists[i - 1].power) * i) % self.mod -        self.lists[N].rev = pow(self.lists[N].power, self.mod - 2, self.mod) -        for j in range(N, 0, -1): -            self.lists[j - 1].rev = ((self.lists[j].rev) * j) % self.mod - -    def combi(self, K, R): -        if K < R: -            return 0 -        else: -            return ( -                (self.lists[K].power) * (self.lists[K - R].rev) * (self.lists[R].rev) -            ) % self.mod - - -    ans -= c.combi(N, i) * pow(25, N - i, mod) +    ans -= c.com(N, i) * pow(25, N - i, mod)