/*
    Author:zeke

    pass System Test!
    GET AC!!
*/
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using ll = long long;
using ld = long double;
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(), (x).end()
#define rep3(var, min, max) for (ll(var) = (min); (var) < (max); ++(var))
#define repi3(var, min, max) for (ll(var) = (max)-1; (var) + 1 > (min); --(var))
#define Mp(a, b) make_pair((a), (b))
#define F first
#define S second
#define Icin(s) \
    ll(s);      \
    cin >> (s);
#define Scin(s) \
    ll(s);      \
    cin >> (s);
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;
}
typedef pair<ll, ll> P;
typedef vector<ll> V;
typedef vector<V> VV;
typedef vector<P> VP;
ll mod = 1e9 + 7;
ll MOD = 1e9 + 7;
ll INF = 1e18;

int modPow(long long a, long long n, long long p) {
  if (n == 0) return 1; // 0乗にも対応する場合
  if (n == 1) return a % p;
  if (n % 2 == 1) return (a * modPow(a, n - 1, p)) % p;
  long long t = modPow(a, n / 2, p);
  return (t * t) % p;
}

long long modMult(long long a, long long b, long long m) {
    long long res = 0;
    long long exp = a % m;
    while (b) {
        if (b & 1) {
            res += exp;
            if (res > m) res -= m;
        }
        exp <<= 1;
        if (exp > m) exp -= m;
        b >>= 1;
    }
    return res;
}
long long powMod(long long a, long long b, long long m) {
    long long res = 1;
    long long exp = a % m;
    while (b) {
        if (b & 1) res = modMult(res, exp, m);
        exp = modMult(exp, exp, m);
        b >>= 1;
    }
    return res;
}
const int MAX = 5*1e6;
long long fac[MAX], finv[MAX], inv[MAX];

// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++) {
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

// 二項係数計算
long long COM(int n, int k) {
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
long long COM_smallK(ll n, ll k) {
    ll res = 1;
    rep3(i, n - k + 1, n + 1) {
        res *= i;
        res %= MOD;
    }
    return res * finv[k] % MOD;
}
// powMod(a,b,MOD)
// O(log(b))?
// cout << "Case #" << index << " :IMPOSSIBLE";
int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    ll k;
    COMinit();
    string s;
    cin>>k>>s;
    ll n=s.size();
    ll res=0;
    rep(i,k+1){
        ll g=COM(n+k-1-i,n-1);
        ll f=modPow(25,k-i,MOD)%MOD*modPow(26,i,MOD);
        if(f>=MOD)f%=MOD;
        ll h=f*g;
        if(h>=MOD)h%=MOD;
        res+=h;
        if(res>=MOD)res%=MOD;
    }
    cout<<res<<endl;
}


Measured memory_bytes: 121448