#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned ll
#define PI acos(-1)
#define vi vector<int>
#define pi pair<int, int>
#define pl pair<ll, ll>
template<typename T> using v2 = vector<vector<T>>;
template<typename T> using v3 = vector<vector<vector<T>>>;
template<class T> istream &operator>>(istream&is,vector<T>&v){for(auto &elemnt:v)is>>elemnt;return is;}
template<class T,class U> istream &operator>>(istream&is,pair<T,U>&p){is>>p.first>>p.second;return is;}
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const int MOD = 1e9 + 7;
const int INF = 1e9 + 200;
const ll INFLL = 2e18 + 200;

template<int64_t mod>
struct ModInt {
    int64_t value;

    ModInt() : value(0) {}
    ModInt(int64_t x) : value(x >= 0 ? x % mod : (mod - ((-x) % mod) % mod)) {}

    ModInt &operator+=(const ModInt &input) {
        value += input.value;
        if (value >= mod) value -= mod;
        return *this;
    }

    ModInt &operator-=(const ModInt &input) {
        value += (mod - input.value);
        if (value >= mod) value -= mod;
        return *this;
    }

    ModInt &operator*=(const ModInt &input) {
        value = value * input.value % mod;
        return *this;
    }

    ModInt &operator/=(const ModInt &input) {
        *this *= input.inverse();
        return *this;
    }

    ModInt inverse() const {
        int64_t base = value, p = mod;
        pair<int64_t, int64_t> save = {1, 0};
        while (p) {
            int64_t temp = base / p;
            swap(base -= temp * p, p);
            swap(save.first -= temp * save.second, save.second);
        }
        return ModInt(save.first);
    }

    ModInt operator-() const { return ModInt(-value); }

    ModInt operator-(const ModInt &input) const { return ModInt(*this) -= input; }

    ModInt operator+(const ModInt &input) const { return ModInt(*this) += input; }

    ModInt operator*(const ModInt &input) const { return ModInt(*this) *= input; }

    ModInt operator/(const ModInt &input) const { return ModInt(*this) /= input; }

    bool operator==(const ModInt &comparsion) const { return value == comparsion.value; }

    bool operator!=(const ModInt &comparsion) const { return value != comparsion.value; }

    friend istream &operator>>(istream &stream, ModInt &input) {
        int64_t temp;
        stream >> temp;
        input = ModInt<mod>(temp);
        return stream;
    }

    friend ostream &operator<<(ostream &stream, const ModInt &input) {
        return stream << input.value;
    }

    ModInt pow(int64_t n) const {
        ModInt ret(1), x(value);
        while (n > 0) {
            if (n & 1) ret *= x;
            x *= x;
            n >>= 1;
        }
        return ret;
    }

    static const int64_t get_mod() { return mod; }
};

using modint = ModInt<MOD>;

class Combination {
private:
    size_t combination_size;
    vector<modint> factorial, inverse, factorial_inverse;

    void combination_init() {
        factorial[0] = factorial[1] = 1;
        inverse[1] = 1;
        factorial_inverse[0] = factorial_inverse[1] = 1;
        for (size_t index = 2; index < combination_size; index++) {
            factorial[index] = factorial[index - 1] * index;
            inverse[index] = modint(0) - inverse[modint::get_mod() % index] * (modint::get_mod() / index);
            factorial_inverse[index] = factorial_inverse[index - 1] * inverse[index];
        }
    }

public:
    explicit Combination(size_t N) : combination_size(N), factorial(N), inverse(N), factorial_inverse(N) {
        combination_init();
    }

    modint P(int n, int k) const {
        if (n < 0 || k < 0) return 0;
        if (n < k) return 0;
        return factorial[n] * factorial_inverse[n - k];
    }

    modint C(int n, int k) const {
        if (k < 0) return 0;
        return P(n, k) * factorial_inverse[k];
    }

    modint H(int n, int k) const {
        if (n < 0 || k < 0) return 0;
        return k == 0 ? 1 : C(n + k - 1, k);
    }
};

int main() {
    int K;
    string S;
    cin >> K >> S;
    Combination comb(2000000);
    modint ans = 0;
    for (int i = 0; i <= K; i++) {
        modint temp = comb.H(S.length(), i) * modint(25).pow(i);
        temp *= modint(26).pow(K - i);
        ans += temp;
    }
    cout << ans << endl;
}

Measured memory_bytes: 51216