// {{{ by unolight
#include <bits/stdc++.h>
#include <unistd.h>
#pragma GCC diagnostic ignored "-Wunused-result"
#define SZ(x) ((int)(x).size())
#define ALL(x) begin(x),end(x)
#define RALL(x) rbegin(x),rend(x)
#define REP(i,n) for ( int i=0; i<int(n); i++ )
#define REP1(i,a,b) for ( int i=(a); i<=int(b); i++ )
#define MP make_pair
#define PB push_back
using namespace std;
typedef int64_t LL;
typedef pair<int,int> PII;
typedef vector<int> VI;
template<class T> void _R( T &x ) { cin>>x; }
void _R( int &x ) { scanf("%d",&x); }
void _R( int64_t &x ) { scanf("%" PRId64,&x); }
void _R( double &x ) { scanf("%lf",&x); }
void _R( char &x ) { scanf(" %c",&x); }
void _R( char *x ) { scanf("%s",x); }
void R() {}
template<class T, class... U> void R( T& head, U&... tail ) { _R(head); R(tail...); }
template<class T> void _W( const T &x ) { cout<<x; }
void _W( const int &x ) { printf("%d",x); }
void _W( const int64_t &x ) { printf("%" PRId64,x); }
void _W( const double &x ) { printf("%.16f\n",x); }
void _W( const char &x ) { putchar(x); }
void _W( const char *x ) { printf("%s",x); }
template<class T> void _W( const vector<T> &x ) { for (auto i = x.begin(); i != x.end(); _W(*i++)) if (i != x.cbegin()) putchar(' '); }
void W() {}
template<class T, class... U> void W( const T& head, const U&... tail ) { _W(head); putchar(sizeof...(tail)?' ':'\n'); W(tail...); }
template<class T> inline bool chmax( T &a, const T &b ) { return b>a ? a=b,true : false; }
template<class T> inline bool chmin( T &a, const T &b ) { return b<a ? a=b,true : false; }
template<class T, class F=less<T>> void sort_uniq( vector<T> &v, F f=F() ) {
    sort(begin(v),end(v),f);
    v.resize(unique(begin(v),end(v))-begin(v));
}
template<class T> using MaxHeap = priority_queue<T>;
template<class T> using MinHeap = priority_queue<T, vector<T>, greater<T>>;
#ifdef UNO
template<class T> void _dump(const char *s, T &&head) { cerr << s << "=" << head << endl; }
template<class T, class... Args> void _dump(const char *s, T &&head, Args &&... tail) {
    for (int c = 0; *s != ',' || c != 0; cerr << *s++) {
        if (*s == '(' || *s == '[' || *s == '{') c++;
        if (*s == ')' || *s == ']' || *s == '}') c--;
    }
    cerr << "=" << head << ", ";
    _dump(s + 1, tail...);
}
#define dump(...) do { fprintf(stderr, "%s:%d - ", __PRETTY_FUNCTION__, __LINE__); _dump(#__VA_ARGS__, __VA_ARGS__); } while (0)
template<class Iter> ostream &_out(ostream &s, Iter b, Iter e) {
    s << "[";
    for (auto it = b; it != e; it++) s << (it == b ? "" : " ") << *it;
    return s << "]";
}
template<class A, class B> ostream &operator<<(ostream &s, const pair<A, B> &p) { return s << "(" << p.first << "," << p.second << ")"; }
template<class T> ostream &operator<<(ostream &s, const vector<T> &c) { return _out(s, ALL(c)); }
template<class T, size_t N> ostream &operator<<(ostream &s, const array<T, N> &c) { return _out(s, ALL(c)); }
template<class T> ostream &operator<<(ostream &s, const set<T> &c) { return _out(s, ALL(c)); }
template<class A, class B> ostream &operator<<(ostream &s, const map<A, B> &c) { return _out(s, ALL(c)); }
#else
#define dump(...)
#endif
// }}}

// {{{ ModInt
template<int _MOD>
struct ModInt {
    static const auto MOD = _MOD;
    template<class T> using integral_only = typename enable_if<is_integral<T>::value>::type;
    int x;   
    constexpr ModInt() : x() {}
    template<class T, integral_only<T>* = nullptr>
    ModInt(T _x=0) {
        x = _x % MOD;
        if(x<0) x+=MOD;
    }
    ModInt operator-() const { return {x == 0? 0 : MOD-x}; }
    ModInt& operator+=(const ModInt a) {
        if ((x += a.x) >= MOD) x -= MOD;
        return *this;
    }
    ModInt& operator-=(const ModInt a) {
        if ((x += MOD-a.x) >= MOD) x -= MOD;
        return *this;
    }
    ModInt& operator*=(const ModInt a) {
        x = (long long)x * a.x % MOD;
        return *this;
    }
    ModInt& operator/=(const ModInt a) {
        return (*this) *= a.inv();
    }
    ModInt operator+(const ModInt a) const { return ModInt(*this) += a; }
    ModInt operator-(const ModInt a) const { return ModInt(*this) -= a; }
    ModInt operator*(const ModInt a) const { return ModInt(*this) *= a; }
    ModInt operator/(const ModInt a) const { return ModInt(*this) /= a; }
    ModInt inv() const {
        // for prime MOD
        return pow(MOD-2);
    }
    ModInt inv2() const {
        // work for non-prime MOD if gcd(x,MOD) = 1
        int a = x, b = MOD, u = 1, v = 0;
        while(b != 0) {
            int t = a / b;
            a -= t * b;
            u -= t * v;
            swap(a, b);
            swap(u, v);
        }
        return u;
    }
    template<class T, integral_only<T>* = nullptr>
    ModInt pow(T t) const {
        ModInt r = 1, p = *this;
        while(t) {
            if(t & 1) r *= p;
            p *= p;
            t >>= 1;
        }
        return r;
    }
    bool operator==(ModInt rhs) const { return x == rhs.x; }
    bool operator!=(ModInt rhs) const { return x != rhs.x; }
    bool operator<(ModInt rhs) const { return x < rhs.x; }
    bool operator<=(ModInt rhs) const { return x <= rhs.x; }
    bool operator>(ModInt rhs) const { return x > rhs.x; }
    bool operator>=(ModInt rhs) const { return x >= rhs.x; }
    friend string to_string(ModInt i) { return to_string(i.x); }
    friend istream& operator>>(istream&i,ModInt&a) { return i>>a.x; }
    friend ostream& operator<<(ostream&o,const ModInt&a) { return o<<a.x; }
};
const int MOD=1000000007;
using mint=ModInt<MOD>;
// }}}

const int N=2e6+10;
mint fact[N],ifact[N];

void comb_init( int n ) {
    fact[0]=1;
    for ( int i=1; i<=n; i++ ) fact[i]=fact[i-1]*i;
    ifact[n]=fact[n].inv();
    for ( int i=n; i>0; i-- ) ifact[i-1]=ifact[i]*i;
}


mint C( int n, int r ) {
    if ( r<0||n<r ) return 0;
    return fact[n]*ifact[r]*ifact[n-r];
}

int main() {
    string s;
    int k;
    cin >> k >> s;
    int n=s.size();
    mint ans=0;
    comb_init(n+k);
    for ( int i=0; i<=k; i++ ) {
        ans+=C(n-1+i,i)*mint(25).pow(i)*mint(26).pow(k-i);
    }
    cout << ans << '\n';
    return 0;
}












Measured memory_bytes: 20064