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

#define int long long
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define rep(i, n) for (int i = 0; i < n; ++i)
#define REP(i, n) for (int i = 0; i < n; ++i)
#define range(i,a,b) ((a)<=(i) && (i)<(b))
#define debug(x) cout << #x << " = " << (x) << endl;
#define fs first
#define sc second
#define pb push_back
#define eb emplace_back
#define SP << " " <<

typedef long long ll;
typedef pair<int, int> P;
typedef tuple<int, int, int> T;
typedef vector<int> vec;
typedef vector<P> pvec;
typedef vector<vector<int>> vvec;
typedef vector<vector<P>> pvvec;
typedef priority_queue<int> PQI;
typedef priority_queue<P> PQP;
typedef priority_queue<int,vector<int>,greater<int>> PQIG;
typedef priority_queue<P,vector<P>,greater<P>> PQPG;

const vector<int> DX = {0, -1, 0, 1, 1, 1, -1, -1};
const vector<int> DY = {1, 0, -1, 0, 1, -1, 1, -1};
constexpr int MOD = (1000000007);
// const int MOD = (998244353);
// const int INF = (1 << 30); // 1073741824
const ll INF = (1LL << 60); // 1152921504606846976
const double PI = (3.141592653589794);
const double EPS = (0.0000000001); // 10^(-10)

template<class T> inline bool chmin(T& a, T b) {if (a > b) {a = b; return 1;} return 0;}
template<class T> inline bool chmax(T& a, T b) {if (a < b) {a = b; return 1;} return 0;}
template<class T> inline T ceil(T a, T b) {return T((a + b - 1) / b);}
template<class T> inline T round(T a, T b) {return T(a / b);}
template< typename T1, typename T2 > istream &operator>>(istream &is, pair< T1, T2 > &p) { is >> p.first >> p.second; return is; }
template <class T> inline void out(T &a) { bool flag=true; for(auto&x:a){if(flag) {flag=false;} else{ cout << ' '; } cout<<x; } cout << endl; }



//----------------------------------------------------------------
int nmax=200000; // 2*(10^5)
vvec G(nmax);


template<int MOD> struct modint {
    long long val;

    constexpr modint(long long v = 0) noexcept : val(v % MOD) {
        if (val < 0) v += MOD;
    }
    constexpr modint operator - () const noexcept {
        return val ? MOD - val : 0;
    }
    
    constexpr int getmod() { return MOD; }
    constexpr modint operator + (const modint& r) const noexcept { return modint(*this) += r; }
    constexpr modint operator - (const modint& r) const noexcept { return modint(*this) -= r; }
    constexpr modint operator * (const modint& r) const noexcept { return modint(*this) *= r; }
    constexpr modint operator / (const modint& r) const noexcept { return modint(*this) /= r; }
    constexpr modint& operator += (const modint& r) noexcept {
        val += r.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr modint& operator -= (const modint& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr modint& operator *= (const modint& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr modint& operator /= (const modint& r) noexcept {
        long long a = r.val, b = MOD, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % MOD;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator == (const modint& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const modint& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator << (ostream &os, const modint<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr istream& operator >> (istream &is, modint<MOD>& x) noexcept {
        return is >> x.val;
    }
    friend constexpr modint<MOD> modpow(const modint<MOD> &a, long long n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};
using mint = modint<MOD>;
typedef vector<mint> mvec;
typedef vector<vector<mint>> mvvec;

// 二項係数ライブラリ
template<class T> struct BC {
    vector<T> fact_, inv_, finv_;
    constexpr BC() {}
    constexpr BC(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
        init(n);
    }
    constexpr void init(int n) noexcept {
        fact_.assign(n, 1);
        inv_.assign(n, 1);
        finv_.assign(n, 1);
        for(int i = 2; i < n; i++){
            fact_[i] = fact_[i-1] * i;
            inv_[i] = -inv_[MOD%i] * (MOD/i);
            finv_[i] = finv_[i-1] * inv_[i];
        }
    }
    constexpr T C(int n, int k) const noexcept {
        if (n < k || n < 0 || k < 0) return 0;
        return fact_[n] * finv_[k] * finv_[n-k];
    }
    constexpr T P(int n, int k) const noexcept {
        if (n < k || n < 0 || k < 0) return 0;
        return fact_[n] * finv_[n-k];
    }
    constexpr T H(int n, int k) const noexcept {
        return C(n + k - 1, k);
    }
    constexpr T fact(int n) const noexcept {
        if (n < 0) return 0;
        return fact_[n];
    }
    constexpr T inv(int n) const noexcept {
        if (n < 0) return 0;
        return inv_[n];
    }
    constexpr T finv(int n) const noexcept {
        if (n < 0) return 0;
        return finv_[n];
    }
};
BC<mint> bc(2000000+10);

int gcd(int x, int y) { return y ? gcd(y, x%y) : x; }
int lcm(int x, int y) { return x/gcd(x, y)*y; }
int mod_pow(int x, int y) { int res = 1; while (y > 0) { if (y & 1) { res = res * x % MOD; } x = x * x % MOD; y >>= 1; } return res; }
int cmb(int n,int k){ if(n<k){ return 0;} int res=1,nn=n,kk=1;k=min(k,n-k); for(int i=0;i<k;i++){ res*=nn-i;res/=kk+i;} return res; }
ll comb(ll n,ll k){ ll res=1; for(int i=0;i<k;i++){ (res*=(n-i)%MOD)%=MOD; } for(int i=1;i<=k;i++){ (res*=mod_pow(i,MOD-2))%=MOD; } return res; }
int to_int(string s) { int n = s.size(); int ans = 0; for (int i = 0; i < n; i++) { ans = ((ans * 10) + (s[i] - '0')) % MOD; } return ans; }
int DigitSum(int x){ int ret=0; while(x){ ret++;x/=10;} return ret; }
bool is_prime(int n) { for(int i = 2; i*i <= n; i++) { if (n % i == 0) return false; } return n != 1; }
int extgcd(int a, int b, int& x, int& y) { // ax+by = gcd(a,b) >> gcd(a,b)
  int d = a;
  if(d != 0) { d = extgcd(b, a%b, y, x); y -= (a/b)*x; }
  else { x = 1, y = 0; }
  return 0;
}

void solve4ts()
{
  
  
  int k;
  cin>>k;
  string s;
  cin>>s;
  mint ans=0;

  int n=s.size()+k;

  for(int i=0;i<n-s.size()+1;i++){
    mint ni=modpow((mint)25,i);
    mint c=bc.C(n,i);
    ans+=ni*c;
  }
  cout<<ans<<endl;

  
}
//-----------------------------------------------------------------

signed main(){ ios::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(15);
    int repeat = 1;
    // cin >> repeat;
    while(repeat--) solve4ts();
}

Measured memory_bytes: 55840