#include <bits/stdc++.h>
using namespace std;

#pragma region Macros
using ll = long long;
#define int ll
using pii = pair<int, int>;
using tiii = tuple<int, int, int>;
template<class T = ll> using V = vector<T>;
template<class T = ll> using VV = V<V<T>>;
#define IOS\
    ios::sync_with_stdio(false);\
    cin.tie(0);\
    cout.tie(0);
#define FOR(i,l,r) for(ll i=(l);i<(r);++i)
#define REP(i,n) FOR(i,0,n)
#define REPS(i,n) FOR(i,1,n+1)
#define RFOR(i,l,r) for(ll i=(l);i>=(r);--i)
#define RREP(i,n) RFOR(i,n-1,0)
#define RREPS(i,n) RFOR(i,n,1)
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(),(x).end()
#define SORT(name) sort(name.begin(), name.end())
#define RSORT(name)\
    SORT(name);\
    reverse(all(name));
#define ZERO(p) memset(p, 0, sizeof(p))
#define MINUS(p) memset(p, -1, sizeof(p))
inline void Yes(bool b = true) {cout << (b ? "Yes" : "No") << '\n';}
inline void YES(bool b = true) {cout << (b ? "YES" : "NO") << '\n';}
template <class T> inline void print(T x){ cout << x << '\n';}
template<typename T1,typename T2> inline void chmin(T1 &a, T2 b){ if(a > b) a = b; }
template<typename T1,typename T2> inline void chmax(T1 &a, T2 b){ if(a < b) a = b; }

const ll LLINF = (1LL<<60);
const int INF = (1LL<<30);
const double DINF = std::numeric_limits<double>::infinity();
#pragma endregion

#if 1
#  define DBG(fmt, ...) printf(fmt, ##__VA_ARGS__)
#else
#  define DBG(fmt, ...)
#endif

template< typename T >
class NumberOfCase {
    public:
        // 初期化 O(n log m) m は素数
        // n : 求めたい組み合わせの最大値
        NumberOfCase(ll n) : m_Size(n) {
            m_Fact.resize(m_Size + 1);
            m_FInv.resize(m_Size + 1);
            m_Inv.resize(m_Size + 1);
            // 0! ～ m_Size! までの階乗を保管する配列の作成 (mod m_Mod をとってある)
            m_Fact[0] = 1;
            for(int i = 1; i <= m_Size; ++i) { m_Fact[i] = m_Fact[i-1] * i; }
            // m_Size! の逆元 1/m_Size! を二分累乗法で求める
            // フェルマーの小定理より a^-1 = a^(p-2) mod p -> (m_Size!)^-1 = (m_Size!)^(p-2) mod p
            m_FInv[m_Size] = T(1) / m_Fact[m_Size];
            // 以下 1 / (N-1)! = N / N! であることを利用
            for(int i = m_Size - 1; i >= 0; --i) { m_FInv[i] = m_FInv[i + 1] * (i + 1); }
            // 逆元の作成（割り算のとき利用）
            m_Inv[0] = 1;
            for(int i = 1; i <= m_Size; ++i) { m_Inv[i] = m_FInv[i] * m_Fact[i - 1]; }
        }
        // 階乗 n! の取得 O(1)
        T Factorial(ll n) const { return m_Fact[n]; }
        // n! の逆元の取得 O(1)
        T FInverse(ll n) const { return m_FInv[n]; }
        // 逆元の取得 O(1) or O(log MOD)
        T Inverse(ll n) const { return m_Inv[n]; }
        // 順列 nPr の取得 O(1)
        T Permutation(ll n, ll r) const {
            if(r < 0 || n < r) { return 0; }
            return m_Fact[n] * m_FInv[n - r];
        }
        // 組み合わせ nCr の取得 O(1)
        T Combination(ll n, ll r) const {
            if(r < 0 || n < r) { return 0; }
            return m_Fact[n] * m_FInv[r]  * m_FInv[n - r];
        }
        // 重複組み合わせ nHr の取得 O(1)
        T Homogen(ll n, ll r) const {
            if(n < 0 || r < 0) { return 0; }
            return (r == 0) ? 1 : Combination(r + n - 1, r);
        }
    private:
        const ll    m_Size;     // 導出する範囲 (10^5 くらいまでにして欲しい)
        vector<T>  m_Fact;     // 階乗
        vector<T>  m_FInv;     // 階乗の逆元
        vector<T>  m_Inv;      // 逆元
};

const int MOD = 1000000007;

// 自動で余りを取ってくれる整数型
// 割り算や負の数による初期化も可能
template< int mod >
struct ModInt {
    int x;
    ModInt() : x(0) {}
    ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
    ModInt &operator+=(const ModInt &p) {
        if((x += p.x) >= mod) x -= mod;
        return *this;
    }
    ModInt &operator-=(const ModInt &p) {
        if((x += mod - p.x) >= mod) x -= mod;
        return *this;
    }
    ModInt &operator*=(const ModInt &p) {
        x = (int) (1LL * x * p.x % mod);
        return *this;
    }
    ModInt &operator/=(const ModInt &p) {
        *this *= p.inverse();
        return *this;
    }
    ModInt operator-() const { return ModInt(-x); }
    ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
    ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
    ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
    ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
    bool operator==(const ModInt &p) const { return x == p.x; }
    bool operator!=(const ModInt &p) const { return x != p.x; }
    ModInt inverse() const {
        int a = x, b = mod, u = 1, v = 0, t;
        while(b > 0) {
            t = a / b;
            swap(a -= t * b, b);
            swap(u -= t * v, v);
        }
        return ModInt(u);
    }
    ModInt pow(int64_t n) const {
        ModInt ret(1), mul(x);
        while(n > 0) {
            if(n & 1) ret *= mul;
            mul *= mul;
            n >>= 1;
        }
        return ret;
    }
    friend ostream &operator<<(ostream &os, const ModInt &p) {
        return os << p.x;
    }
    friend istream &operator>>(istream &is, ModInt &a) {
        int64_t t;
        is >> t;
        a = ModInt< mod >(t);
        return (is);
    }
    static int get_mod() { return mod; }
};
using modint = ModInt< MOD >;

const int MAX_N = 2000010;

int K;
string S;

signed main() {
    IOS;

    NumberOfCase<modint> noc(MAX_N);

    cin >> K >> S;

    modint ans(0);
    REP(i, K + 1) {
        modint n(26), m(25);
        ans += n.pow(i) * m.pow(K - i) * noc.Combination(S.length() + K - i - 1, S.length() - 1);
    }
    print(ans);

    return 0;
}


Measured memory_bytes: 51120