#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
#define rep(i,s,e) for(i64 (i) = (s);(i) < (e);(i)++)
#define all(x) x.begin(),x.end()

template<class T>
static inline std::vector<T> ndvec(size_t&& n, T val) { return std::vector<T>(n, std::forward<T>(val)); }
template<class... Tail>
static inline auto ndvec(size_t&& n, Tail&&... tail) {
  return std::vector<decltype(ndvec(std::forward<Tail>(tail)...))>(n, ndvec(std::forward<Tail>(tail)...));
}
template<class Cond> struct chain {
  Cond cond; chain(Cond cond) : cond(cond) {}
  template<class T> bool operator()(T& a, const T& b) const { if(cond(a, b)) { a = b; return true; } return false; }
};
template<class Cond> chain<Cond> make_chain(Cond cond) { return chain<Cond>(cond); }

#include <iostream>
using i64 = long long;
template<i64 M> struct modint { i64 a;
  constexpr modint(const i64 x = 0): a((x%M+M)%M){}
  constexpr i64 value() const { return a; }
  constexpr modint inv() const { return this->pow(M-2); }
  constexpr modint pow(i64 r) const {
    modint ans(1); modint aa = *this;
    while(r) { if(r & 1) ans *= aa; aa *= aa; r >>= 1; }
    return ans;
  }
  constexpr modint& operator=(const i64 r) { a = (r % M + M) % M; return *this; }
  constexpr modint& operator+=(const modint r) { a += r.a; if(a >= M) a -= M; return *this; }
  constexpr modint& operator-=(const modint r) { a -= r.a; if(a < 0) a += M; return *this; }
  constexpr modint& operator*=(const modint r) { a = a * r.a % M; return *this; }
  constexpr modint& operator/=(const modint r) { (*this) *= r.inv(); return *this; }
  constexpr modint operator+(const modint r) const { return modint(*this) += r; }
  constexpr modint operator-(const modint r) const { return modint(*this) -= r; }
  constexpr modint operator*(const modint r) const { return modint(*this) *= r; }
  constexpr modint operator/(const modint r) const { return modint(*this) /= r; }
  constexpr bool operator!=(const modint r) const { return this->value() != r.value(); }
};

template<const i64 M> std::ostream& operator<<(std::ostream& os, const modint<M>& m) { os << m.value(); return os; }

#include <vector>
#include <tuple>
using i64 = long long;

template<class T>
std::tuple<std::vector<T>, std::vector<T>, std::vector<T>> build_factorial(int N) {
  std::vector<T> fact(N);
  std::vector<T> finv(N);
  std::vector<T> inv(N);
  fact[0] = T(1);
  for(int i = 1;i < N;i++) {
    fact[i] = fact[i - 1] * T(i);
  }
  finv[N - 1] = T(1) / fact[N - 1];
  for(int i = N - 1; i --> 0;) {
    finv[i] = finv[i + 1] * T(i + 1);
  }
  for(int i = 0;i < N;i++) {
    inv[i] = fact[i - 1] * finv[i];
  }
  return std::make_tuple(std::move(fact), std::move(finv), std::move(inv));
}

using fp = modint<(i64)(1e9 + 7)>;

int main() {
  i64 K;
  string S;
  cin >> K >> S;
  i64 N = S.size();

  auto [fact, finv, inv] = build_factorial<fp>((i64)(2e6));

  vector<fp> P;
  P.push_back(fp(1));
  rep(i,0,fact.size()) {
    P.push_back(P[i] * fp(25));
  }
  vector<fp> Q;
  Q.push_back(fp(1));
  rep(i,0,fact.size()) {
    Q.push_back(Q[i] * fp(26));
  }
  fp ans(0);

  rep(i,N, N + K + 1) {
    i64 b = N + K - i;
    i64 a = i - N;
    ans += fact[i - 1] * finv[N - 1] * finv[i - N] * P[a] * Q[b];
  }
  cout << ans << endl;
}



Measured memory_bytes: 91380