mod = pow(10, 9)+7

k = int(eval(input()))

s = eval(input())

n = len(s)

ans = 0

key = pow(26, k, mod)

sub = 1

c = 1

for i in range(k+1):

    ans += key*sub*c

    ans %= mod

    sub *= 25

    sub %= mod

    key = key*pow(26, mod-2, mod)%mod

    c *= (n+i)

    c *= pow(i+1, mod-2, mod)

    c %= mod

print(ans)
def main():

    mod = pow(10, 9)+7

    k = int(eval(input()))

    s = eval(input())

    n = len(s)

    ans = 0

    key = pow(26, k, mod)

    sub = 1

    c = 1

    for i in range(k+1):

        ans += key*sub*c

        ans %= mod

        sub *= 25

        sub %= mod

        key = key*pow(26, mod-2, mod)%mod

        c *= (n+i)

        c *= pow(i+1, mod-2, mod)

        c %= mod

    print(ans)



if __name__ == "__main__":

    main()

mod = pow(10, 9) + 7
k = int(eval(input()))
s = eval(input())
n = len(s)
ans = 0
key = pow(26, k, mod)
sub = 1
c = 1
for i in range(k + 1):
    ans += key * sub * c
    ans %= mod
    sub *= 25
    sub %= mod
    key = key * pow(26, mod - 2, mod) % mod
    c *= n + i
    c *= pow(i + 1, mod - 2, mod)
    c %= mod
print(ans)

def main():
    mod = pow(10, 9) + 7
    k = int(eval(input()))
    s = eval(input())
    n = len(s)
    ans = 0
    key = pow(26, k, mod)
    sub = 1
    c = 1
    for i in range(k + 1):
        ans += key * sub * c
        ans %= mod
        sub *= 25
        sub %= mod
        key = key * pow(26, mod - 2, mod) % mod
        c *= n + i
        c *= pow(i + 1, mod - 2, mod)
        c %= mod
    print(ans)


if __name__ == "__main__":
    main()

-mod = pow(10, 9) + 7 -k = int(eval(input())) -s = eval(input()) -n = len(s) -ans = 0 -key = pow(26, k, mod) -sub = 1 -c = 1 -for i in range(k + 1): -    ans += key * sub * c -    ans %= mod -    sub *= 25 -    sub %= mod -    key = key * pow(26, mod - 2, mod) % mod -    c *= n + i -    c *= pow(i + 1, mod - 2, mod) -    c %= mod -print(ans) +def main(): +    mod = pow(10, 9) + 7 +    k = int(eval(input())) +    s = eval(input()) +    n = len(s) +    ans = 0 +    key = pow(26, k, mod) +    sub = 1 +    c = 1 +    for i in range(k + 1): +        ans += key * sub * c +        ans %= mod +        sub *= 25 +        sub %= mod +        key = key * pow(26, mod - 2, mod) % mod +        c *= n + i +        c *= pow(i + 1, mod - 2, mod) +        c %= mod +    print(ans) + + +if __name__ == "__main__": +    main()