/*
                                        //     //     //\\\\\\\\\
                                        \\    //      \\        \\
                                        //   //       //         \\
                                        \\  //        \\          \\
                                        // //         //           \\
                                        \\//          \\            \\       
                                        //\\          //            //
                                        \\ \\         \\           //
                                        //  \\        //          //
                                        \\   \\       \\         //
                                        //    \\      //        //
                                        \\     \\     \\/////////
*/

#include <bits/stdc++.h>
//#include <boost/math/common_factor.hpp>
//#include <boost/multiprecision/cpp_int.hpp>
using namespace std;
//using namespace boost::multiprecision;
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define vint vector <int>
#define vll vector <long long int>
#define endl cout<<'\n'
#define fre(i,l,n) for(long long int i=l;i<n;++i)
#define fr(i,l,n) for(long long int i=l;i<=n;i++)
#define rfre(i,n,l) for(long long int i=n-1;i>=l;i--)
#define rfr(i,n,l) for(long long int i=n;i>=l;--i)
#define tab '\t'
#define debug cout<<'*';
#define s(a) cin>>a
#define p(a) cout<<a
typedef long long int ll;
typedef unsigned long long int ull;
typedef pair<int,int> pii;
typedef pair<long long int,long long int> pll;
typedef pair<int,pair<int,int> > tii;
typedef vector<int> vec;
typedef vector<long long> vecll;
typedef vector<pair<int,int> > vec_pii;
typedef vector<pair<long long int,long long int> > vec_pll;
typedef vector<vector<int> > vvi;
typedef vector<vector<ll> > vvll;
typedef vector<vector<pair<int,int> > > vvpii;
typedef vector<vector<pair<ll,ll> > > vvpll;
#define mp make_pair
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define mod 1000000007
#define Pi 3.14159265358979
#define gcd(a,b) __gcd(a,b)
#define sf(n) scanf("%lld",&(n))
#define pf(n) printf("%lld\n",(n))
#define min3(a,b,c) (min((c),min((a),(b))))
#define max3(a,b,c) (max((a),max((b),(c))))
#define w(t) while(t--)
#define flt(a) cout<<fixed<<setprecision(a)
#define cntSetBits(n) __builtin_popcountll(n)
/*****************************
*****************************/


const ll MAXN = 2000000;


ll fact[MAXN+5];
ll invfact[MAXN+5];


ll power(ll a, ll b)
{
    ll res = 1;
    while(b)
    {
        if(b & 1)
        {
            res = (res%mod * a%mod)%mod;
        }
        a = (a%mod * a%mod)%mod;
        b >>= 1;
    }
    return res;
}


void facto()
{
    fact[0] = 1;
    fr(i,1,MAXN)
    {
        fact[i] = (fact[i-1]%mod * i%mod)%mod;
    }
    invfact[MAXN] = power(fact[MAXN],mod-2);
    rfre(i,MAXN,0)
    {
        invfact[i] = (invfact[i+1]%mod * (i+1)%mod)%mod;
    }
}



ll nCr(ll n,ll r)
{
    return (fact[n]%mod * invfact[r]%mod * invfact[n-r]%mod)%mod;
}



void solve()
{
    ll k;
    s(k);
    string str;
    s(str);
    ll n = (ll)str.length();
    ll ans = 0;
    fr(i,n,n+k)
    {
        ans = (ans%mod + (nCr(n+k,i)%mod * power(25,n+k-i)%mod)%mod)%mod;
    }
    p(ans);endl;
}



int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    facto();
    ll t=1;
    // s(t);
    w(t)
    {
        solve();
    }
    return 0;
}









Measured memory_bytes: 35504