class Combination:

    def __init__(self, n, mod):

        self.mod = mod



        # self.fac[i] ≡ i! (factorial:階乗)

        l = [1]

        num = 1

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

            num *= i

            num %= mod

            l.append(num)

        self.fac = l.copy()



        # self.rec[i] ≡ 1 / i! (reciprocal:逆数)

        num = pow(num, mod-2, mod)

        l = [1 for i in range(n+1)]

        l[n] = num

        for i in range(n-1, 0, -1):

            num *= i + 1

            num %= mod

            l[i] = num

        self.rec = l.copy()



    # comb(n, r) ≡ nCr

    def comb(self, n, r):

        return self.fac[n] * self.rec[r] * self.rec[n - r] % self.mod



mod = 10**9 + 7



k = int(eval(input()))

s = eval(input())

n = len(s)



c = Combination(k + n, mod)



ans = 0

for i in range(k+1):

    ans += c.comb(n + i - 1, i) * pow(25, i, mod) * pow(26, k-i, mod)

    ans %= mod



print(ans)
class Combination:

    def __init__(self, n, mod):

        self.mod = mod



        # self.fac[i] ≡ i! (factorial:階乗)

        l = [1]

        num = 1

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

            num *= i

            num %= mod

            l.append(num)

        self.fac = l.copy()



        # self.rec[i] ≡ 1 / i! (reciprocal:逆数)

        num = pow(num, mod-2, mod)

        l = [1 for i in range(n+1)]

        l[n] = num

        for i in range(n-1, 0, -1):

            num *= i + 1

            num %= mod

            l[i] = num

        self.rec = l.copy()



    # comb(n, r) ≡ nCr

    def comb(self, n, r):

        return self.fac[n] * self.rec[r] * self.rec[n - r] % self.mod



mod = 10**9 + 7



k = int(eval(input()))

s = eval(input())

n = len(s)



c = Combination(k + n, mod)



pow25 = [1]

pow26 = [1]

for _ in range(k):

    pow25.append(25 * pow25[-1] % mod)

    pow26.append(26 * pow26[-1] % mod)



ans = 0

for i in range(k+1):

    ans += c.comb(n+i-1, i) * pow25[i] * pow26[k-i]

    ans %= mod



print(ans)
class Combination:
    def __init__(self, n, mod):
        self.mod = mod
        # self.fac[i] ≡ i! (factorial:階乗)
        l = [1]
        num = 1
        for i in range(1, n + 1):
            num *= i
            num %= mod
            l.append(num)
        self.fac = l.copy()
        # self.rec[i] ≡ 1 / i! (reciprocal:逆数)
        num = pow(num, mod - 2, mod)
        l = [1 for i in range(n + 1)]
        l[n] = num
        for i in range(n - 1, 0, -1):
            num *= i + 1
            num %= mod
            l[i] = num
        self.rec = l.copy()

    # comb(n, r) ≡ nCr
    def comb(self, n, r):
        return self.fac[n] * self.rec[r] * self.rec[n - r] % self.mod


mod = 10**9 + 7
k = int(eval(input()))
s = eval(input())
n = len(s)
c = Combination(k + n, mod)
ans = 0
for i in range(k + 1):
    ans += c.comb(n + i - 1, i) * pow(25, i, mod) * pow(26, k - i, mod)
    ans %= mod
print(ans)

class Combination:
    def __init__(self, n, mod):
        self.mod = mod
        # self.fac[i] ≡ i! (factorial:階乗)
        l = [1]
        num = 1
        for i in range(1, n + 1):
            num *= i
            num %= mod
            l.append(num)
        self.fac = l.copy()
        # self.rec[i] ≡ 1 / i! (reciprocal:逆数)
        num = pow(num, mod - 2, mod)
        l = [1 for i in range(n + 1)]
        l[n] = num
        for i in range(n - 1, 0, -1):
            num *= i + 1
            num %= mod
            l[i] = num
        self.rec = l.copy()

    # comb(n, r) ≡ nCr
    def comb(self, n, r):
        return self.fac[n] * self.rec[r] * self.rec[n - r] % self.mod


mod = 10**9 + 7
k = int(eval(input()))
s = eval(input())
n = len(s)
c = Combination(k + n, mod)
pow25 = [1]
pow26 = [1]
for _ in range(k):
    pow25.append(25 * pow25[-1] % mod)
    pow26.append(26 * pow26[-1] % mod)
ans = 0
for i in range(k + 1):
    ans += c.comb(n + i - 1, i) * pow25[i] * pow26[k - i]
    ans %= mod
print(ans)

+pow25 = [1] +pow26 = [1] +for _ in range(k): +    pow25.append(25 * pow25[-1] % mod) +    pow26.append(26 * pow26[-1] % mod) -    ans += c.comb(n + i - 1, i) * pow(25, i, mod) * pow(26, k - i, mod) +    ans += c.comb(n + i - 1, i) * pow25[i] * pow26[k - i]