def prepare(n):

    global MOD

    modFacts = [0] * (n + 1)

    modFacts[0] = 1

    for i in range(n):

        modFacts[i + 1] = (modFacts[i] * (i + 1)) % MOD



    invs = [1] * (n + 1)

    invs[n] = pow(modFacts[n], MOD - 2, MOD)

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

        invs[i - 1] = (invs[i] * i) % MOD



    return modFacts, invs





MOD = 10 ** 9 + 7

K = int(eval(input()))

S = eval(input())

L = len(S)

modFacts, invs = prepare(K + L)



ans = 0

for n in range(L, L + K + 1):

    nonSi = (pow(25, n - L, MOD) * pow(26, L + K - n, MOD)) % MOD

    Si = (modFacts[n - 1] * invs[L - 1] * invs[n - 1 - (L - 1)]) % MOD

    ans += nonSi * Si

    ans %= MOD



print(ans)

def prepare(n):

    global MOD

    modFacts = [0] * (n + 1)

    modFacts[0] = 1

    for i in range(n):

        modFacts[i + 1] = (modFacts[i] * (i + 1)) % MOD



    invs = [1] * (n + 1)

    invs[n] = pow(modFacts[n], MOD - 2, MOD)

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

        invs[i - 1] = (invs[i] * i) % MOD



    return modFacts, invs





MOD = 10 ** 9 + 7

K = int(eval(input()))

S = eval(input())

L = len(S)

modFacts, invs = prepare(K + L)



pow25 = [1] * max(L + 1, K + 1)

pow26 = [1] * max(L + 1, K + 1)

for i in range(max(L, K)):

    pow25[i + 1] = (pow25[i] * 25) % MOD

    pow26[i + 1] = (pow26[i] * 26) % MOD



ans = 0

for n in range(L, L + K + 1):

    nonSi = (pow25[n - L] * pow26[L + K - n]) % MOD

    Si = (modFacts[n - 1] * invs[L - 1] * invs[n - 1 - (L - 1)]) % MOD

    ans += nonSi * Si

    ans %= MOD



print(ans)

def prepare(n):
    global MOD
    modFacts = [0] * (n + 1)
    modFacts[0] = 1
    for i in range(n):
        modFacts[i + 1] = (modFacts[i] * (i + 1)) % MOD
    invs = [1] * (n + 1)
    invs[n] = pow(modFacts[n], MOD - 2, MOD)
    for i in range(n, 1, -1):
        invs[i - 1] = (invs[i] * i) % MOD
    return modFacts, invs


MOD = 10**9 + 7
K = int(eval(input()))
S = eval(input())
L = len(S)
modFacts, invs = prepare(K + L)
ans = 0
for n in range(L, L + K + 1):
    nonSi = (pow(25, n - L, MOD) * pow(26, L + K - n, MOD)) % MOD
    Si = (modFacts[n - 1] * invs[L - 1] * invs[n - 1 - (L - 1)]) % MOD
    ans += nonSi * Si
    ans %= MOD
print(ans)

def prepare(n):
    global MOD
    modFacts = [0] * (n + 1)
    modFacts[0] = 1
    for i in range(n):
        modFacts[i + 1] = (modFacts[i] * (i + 1)) % MOD
    invs = [1] * (n + 1)
    invs[n] = pow(modFacts[n], MOD - 2, MOD)
    for i in range(n, 1, -1):
        invs[i - 1] = (invs[i] * i) % MOD
    return modFacts, invs


MOD = 10**9 + 7
K = int(eval(input()))
S = eval(input())
L = len(S)
modFacts, invs = prepare(K + L)
pow25 = [1] * max(L + 1, K + 1)
pow26 = [1] * max(L + 1, K + 1)
for i in range(max(L, K)):
    pow25[i + 1] = (pow25[i] * 25) % MOD
    pow26[i + 1] = (pow26[i] * 26) % MOD
ans = 0
for n in range(L, L + K + 1):
    nonSi = (pow25[n - L] * pow26[L + K - n]) % MOD
    Si = (modFacts[n - 1] * invs[L - 1] * invs[n - 1 - (L - 1)]) % MOD
    ans += nonSi * Si
    ans %= MOD
print(ans)

+pow25 = [1] * max(L + 1, K + 1) +pow26 = [1] * max(L + 1, K + 1) +for i in range(max(L, K)): +    pow25[i + 1] = (pow25[i] * 25) % MOD +    pow26[i + 1] = (pow26[i] * 26) % MOD -    nonSi = (pow(25, n - L, MOD) * pow(26, L + K - n, MOD)) % MOD +    nonSi = (pow25[n - L] * pow26[L + K - n]) % MOD