/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

//<editor-fold desc="definitions">
#include <bits/stdc++.h>
#define se cout << "test ok" << endl;
#define sp << " " <<
#define enl "\n"
using namespace std;
using ll=long long;
using ld=long double;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using vi = vector<int>;
using vii = vector<vector<int>>;
using viii = vector<vector<vector<int>>>;
using vl = vector<ll>;
using vll = vector<vector<ll>>;
using vlll = vector<vector<vector<ll>>>;
template<class T> using V = vector<T>;
template<class T> using VV = vector<vector<T>>;
template<class T> using VVV = vector<vector<vector<T>>>;
template<class T1, class T2> using P = pair<T1, T2>;
ll mod = ll(1e9)+7;
ll inf = ll(1e18);
void bl(bool b, ostream& out=cout){ out << (b ? "Yes" : "No") << endl; }
void bl2(bool b, ostream& out=cout){ out << (b ? "YES" : "NO") << endl; }
template<typename T> inline bool chmax(T &a, T b){ if(a<b){a=b; return true;} return false; }
template<typename T> inline bool chmin(T &a, T b){ if(a>b){a=b; return true;} return false; }
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#define TO_STRING(varName) # varName
#include <iostream>
#include <vector>
#include <map>
#include <set>
using namespace std;

namespace dbg {

using ll = long long;

class Debug {
  void prefix() { cout << "\033[7m\033[35m" << " DEBUG " << "\033[0m" << endl; }

  void out_helper(){ cout << endl; }

  void out_with_name_helper(){ cout << endl; }

  template<typename T1, typename... T2>
  void out_helper(T1 v, T2... args);

  template<typename T1, typename... T2>
  void out_with_name_helper(string s, T1 v, T2... args);

  // value
  template<typename T>
  void print(T val);

  // pair
  template<typename A, typename B>
  void print(pair<A, B> p);

  // tuple
  template<typename A, typename B, typename C>
  void print(tuple<A, B, C> t);

  // vector
  template<typename T>
  void print(vector<T> &vec);

  // set
  template<typename T>
  void print(set<T> &st);

  // map
  template<typename A, typename B>
  void print(map<A, B> mp);
public:
  Debug(){}

  template<typename... T>
  void out(T... args){
    prefix();
    out_helper(args...);
  }

  template<typename... T>
  void out_with_name(T... args){
    prefix();
    out_with_name_helper(args...);
  }

  template<typename T>
  void outg(vector<vector<T>> &g) {
    prefix();
    for(auto& v1 : g){
      for(auto& v2 : v1) {
        cout << v2 << " ";
      }
      cout << endl;
    }
  }
};

template<typename T1, typename... T2>
void Debug::out_helper(T1 v, T2... args) {
  print(v); cout << endl;
  out_helper(args...);
}

template<typename T1, typename... T2>
void Debug::out_with_name_helper(string s, T1 v, T2... args) {
  cout << s << ": "; print(v); cout << endl;
  out_with_name_helper(args...);
}

template<typename T>
void Debug::print(T val){
  cout << val;
}

template<typename A, typename B>
void Debug::print(pair<A, B> p){
  cout << "("; print(p.first); cout << ", "; print(p.second); cout << ")";
}

template<typename A, typename B, typename C>
void Debug::print(tuple<A, B, C> t) {
  cout << "("; print(get<0>(t)); cout << ", "; print(get<1>(t)); cout << ", "; print(get<2>(t)); cout << ")";
}

template<typename T>
void Debug::print(vector<T>& vec) {
  cout << "[";
  bool fir = true;
  for(auto& e : vec) {
    if(!fir) cout << " ";
    print(e), fir=false;
  }
  cout << "]";
}

template<typename T>
void Debug::print(set<T> &st){
  cout << "{";
  bool fir = true;
  for(auto& e : st) {
    if(!fir) cout << " ";
    print(e), fir=false;
  }
  cout << "}";
}

template<typename A, typename B>
void Debug::print(map<A, B> mp){
  cout << "{";
  bool fir = true;
  for(auto& p : mp){
    if(!fir) cout << " ";
    print(p), fir=false;
  }
  cout << "}";
}

}

#endif //INCLUDE_DEBUG_HPP

dbg::Debug debug;
//</editor-fold>

#ifndef DEFINE_MATH_HPP
#define DEFINE_MATH_HPP


using namespace std;

namespace math {

using ll = long long;

class Math {
    ll mod;
public:
  Math(ll mod = 1e9+7):mod(mod){}
  ll keta(ll num);
  ll gcd(ll a, ll b);
  ll lcm(ll a, ll b);
  ll powm(ll num1, ll num2);
  bool isPrime(ll n);
  vector<ll> changeBase(ll n, int b);
};

ll Math::gcd(ll a, ll b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}

ll Math::lcm(ll a, ll b) {
  return a * (b / gcd(a, b));
}

ll Math::keta(ll num) {
  ll k = 0;
  while (num > 0) {
      num /= 10;
      k++;
  }
  return k;
}

ll Math::powm(ll a, ll b) {
  ll res = 1;
  while (b > 0) {
      if (b & 1) (res *= a) %= mod;
      (a *= a) %= mod;
      b >>= 1;
  }
  return res;
}

bool Math::isPrime(ll n) {
  bool flg = true;
  for(ll i=2; i*i<=n; i++){
      if(n%i == 0) {
          flg = false;
          break;
      }
  }
  return flg;
}

vector<ll> Math::changeBase(ll n, int b){
  vector<ll> v;
  while(n > 0){
    ll r = n%b;
    if(r == 0) --n;
    n /= n;
    v.push_back((r-1+b)%b);
  }
  return v;
}

}

#endif //DEFINE_MATH_HPP

math::Math mt;

#ifndef DEFINE_COMBINATION_HPP
#define DEFINE_COMBINATION_HPP


using namespace std;

namespace comb {

using ll = long long;

class Comb {
private:
  ll mod;

  ll powm(ll a, ll b) {
    ll res = 1;
    while(b > 0){
      if(b & 1) (res *= a) %= mod;
      (a *= a) %= mod;
      b >>= 1;
    }
    return res;
  }

public:
  vector<ll> fact;
  vector<ll> finv;
  vector<ll> inv;

  Comb(ll mod = 1e9+7):mod(mod) {};
  Comb(int n, ll mod = 1e9+7):mod(mod) { build(n); }
  void build(int n);
  ll res(int n, int k); // return nCk
  ll resone(ll n, ll k);
};

void Comb::build(int n) {
  inv.assign(n + 1, 0);
  fact.assign(n + 1, 0);
  finv.assign(n + 1, 0);
  fact[0] = fact[1] = finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i <= n; i++) {
    fact[i] = fact[i - 1] * i % mod;
    inv[i] = mod - inv[mod % i] * (mod / i) % mod;
    finv[i] = finv[i - 1] * inv[i] % mod;
  }
}

ll Comb::res(int n, int k) {
  if (n < k) return 0;
  if (n < 0 || k < 0) return 0;
  return fact[n] * (finv[k] * finv[n - k] % mod) % mod;
}

ll Comb::resone(ll n, ll k) {
  ll res = 1;
  for (ll i = 0; i < k; i++) {
    (res *= (n-i)) %= mod;
    (res *= this->powm(i+1, mod-2)) %= mod;
  }
  return res;
}

}

#endif //DEFINE_COMBINATION_HPP


// verify
// https://atcoder.jp/contests/abc034/tasks/abc034_c

using comb::Comb;

#ifndef INCLUDE_MINT_HPP
#define INCLUDE_MINT_HPP

#include <ostream>

namespace mint {

using ll = long long;

class Mint {
public:
  ll v;
  ll mod;

  Mint(ll v=0, ll mod=ll(1e9)+7) : mod(mod), v((v % mod + mod) % mod) {}

  friend std::ostream& operator<<(std::ostream& os, const Mint& val) {
    os << val.v;
    return os;
  }

  Mint operator-() const { return Mint(-v); }
  Mint operator+(const Mint rhs) const {
    Mint res(*this);
    return res += rhs;
  }
  Mint operator-(const Mint rhs) const {
    Mint res(*this);
    return res -= rhs;
  }
  Mint operator*(const Mint rhs) const {
    Mint res(*this);
    return res *= rhs;
  }
  Mint &operator+=(const Mint rhs) {
    if ((v += rhs.v) >= mod) v -= mod;
    return *this;
  }
  Mint &operator-=(const Mint rhs) {
    if ((v += mod - rhs.v) >= mod) v -= mod;
    return *this;
  }
  Mint &operator*=(const Mint rhs) {
    (v *= rhs.v) %= mod;
    return *this;
  }
  Mint pow(ll t) const {
    if (!t) return 1;
    Mint b = pow(t >> 1);
    b *= b;
    if (t & 1) b *= *this;
    return b;
  }
  Mint inv() const {
    return pow(mod - 2);
  }
  Mint &operator/=(const Mint rhs) {
    return (*this) *= rhs.inv();
  }
  Mint operator/(const Mint rhs) const {
    Mint res(*this);
    return res /= rhs;
  }
};

}

#endif //INCLUDE_MINT_HPP

using mint::Mint;

class FStrivore {
public:
  void solve(std::istream& in, std::ostream& out){
    int k;
    string s;
    in >> k >> s;

    int n = s.length();
    Comb comb;
    comb.build(n+k);
    Mint ans;
    for(int i=0; i<=k; i++){
      ans += (Mint)mt.powm(26, k-i)*(Mint)mt.powm(25, i)*comb.res(n+i-1, n-1);
    }

    out << ans << endl;
  }
};


int main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  FStrivore solver;
  std::istream& in(std::cin);
  std::ostream& out(std::cout);
  solver.solve(in, out);
  return 0;
}


Measured memory_bytes: 51236