#define _CRT_SECURE_NO_WARNINGS


#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <cstring>
#include <numeric>
#include <algorithm>
#include <functional>
#include <fstream>
#include <array>
#include <map>
#include <queue>
#include <time.h>
#include <limits.h>
#include <set>
#include <stack>
#include <random>
#include <complex>
#include <unordered_map>
#include <assert.h>
#include <bitset>
#include <unordered_set>
#define rep(i,s,n) for(int i = (s); (n) > i; i++)
#define REP(i,n) rep(i,0,n)
#define RANGE(x,a,b) (min(a,b) <= (x) && (x) <= max(a,b)) //hei
#define DUPLE(a,b,c,d) (RANGE(a,c,d) || RANGE(b,c,d) || RANGE(c,a,b) || RANGE(d,a,b))
#define INCLU(a,b,c,d) (RANGE(a,c,d) && (b,c,d))
#define PW(x) ((x)*(x))
#define ALL(x) (x).begin(), (x).end()
#define RALL(x) (x).rbegin(), (x).rend()
#define MODU 1000000007LL 
#define bitcheck(a,b)   ((a >> b) & 1)
#define bitset(a,b)      ( a |= (1 << b))
#define bitunset(a,b)    (a &= ~(1 << b))
#define MP(a,b) make_pair((a),(b))
#define Manh(a,b) (abs((a).first-(b).first) + abs((a).second - ((b).second))
#define pritnf printf
#define scnaf scanf
#define itn int
#define PI 3.141592653589
 
 
#define izryt bool
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
template<typename A, size_t N, typename T>
void Fill(A(&array)[N], const T & val) {
	std::fill((T*)array, (T*)(array + N), val);
}
 
//[a, b)
#define Getsum(ar, a,b) (ar[b] - ar[a])
#define INF 10000000000000000LL

 
struct Edge {
	int from, to;
	ll w;
	bool operator<(const Edge& rhs) const {
		return MP(w, MP(from, to)) < MP(rhs.w, MP(rhs.from, rhs.to));
	}
 
};
typedef vector<vector<Edge>> Graph;
typedef unsigned long long ull;
 
 
inline ll ksum(ll n, ll k){
  return k * (2*n - k - 1);
}

pii updtp2(pii p, int nw){
  if(p.first == -1) p.first = nw;
  else if(p.second == -1) p.second = nw;
  else if(p.first >= nw) {
    p.second = p.first;
    p.first = nw;
  }
  else if(p.second >= nw) p.second = nw;
  return p;
}
 
#define isValid(y,x) (y >=0 && y < n && x >= 0 && x < m)

const pii Dir[4] = {{-1,0}, {0,1}, {1,0}, {0,-1}};

ll mod_pow(ll x, ll n, ll mod) {
	ll res = 1;
	while (n > 0) {
		if (n & 1) res = (res * x) %mod;
		x = (x*x)%mod;
		n >>= 1;
	}
	return res;
}

struct UnionFind {
	vector<int> data;
	UnionFind(int size) : data(size, -1) { }
	bool unionSet(int x, int y) { //ｘの入ってる集合と yの入ってる集合を併合
		x = root(x); y = root(y);
		if (x != y) {
			if (data[y] < data[x]) swap(x, y);
			data[x] += data[y]; data[y] = x;
		}
		return x != y;
	}
	bool findSet(int x, int y) { //xとyが同じ集合に入っているかどうかを判定
		return root(x) == root(y);
	}
	int root(int x) {
		return data[x] < 0 ? x : data[x] = root(data[x]);
	}
	bool isroot(int x) {
		return data[x] < 0;
	}
	int size(int x) {
		return -data[root(x)];
	}
};
ll divmod(ll a, ll b, ll m) { // a/b(mod m)
								  // a/b (mod m)
								  // a*b^-1
								  // b^-1 * b = 1
								  // b^(m-1) = 1 
								  // b^(m-2) * b = 1
								  // b^-1 = b^(m-2)

								  // a/b = a * b^(m-2)

	return (a * 1LL * mod_pow(b, m - 2, m)) % m;
}
int main(){
    int k;
    string s;
    cin >> k >> s;
    int l = s.length();
    vector<ll> a(k + 1), fac(k + l + 1);
    fac[0] = 1;
    rep(i,1,k + l + 1) fac[i] = i * fac[i-1]%MODU;
    REP(i,k + 1){// binom(i+s-1, s-1)
        ll n = i + n - 1;
        a[i] = divmod(fac[i+l-1] , (fac[i+l-1-(l-1)] * fac[l-1])%MODU, MODU );
    }

    rep(i,1,k + 1){
        a[i] = a[i] * mod_pow(25, i, MODU) % MODU;
    }
    reverse(ALL(a));

    ll ans = 0;
    REP(i,k + 1){
        ans += a[i] * mod_pow(26, i, MODU) % MODU;
        ans %= MODU;
    }
    cout << ans << endl;

	return 0;
} 

Measured memory_bytes: 27680