#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define pb push_back
#define IOS ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define ll long long
#define gcd(a,b) __gcd((a),(b))
#define lcm(a,b) ((a)*(b))/__gcd((a),(b))
#define vi vector<int>
#define vll vector<long long>
#define vvi vector<vi>
#define mt make_tuple
#define mp make_pair
#define hell 1000000007
#define mod 998244353
#define pii pair<int,int>
#define pll pair<ll,ll>
#define vpii vector<pii>
#define vpll vector<pll>
#define all(a) a.begin(),a.end()
#define ign cin.ignore();
#define g(a,b) get<a>(b)
#define vt(a) vector<a>
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define repi(i,a,b) for(ll i=b-1;i>=a;i--)
#define fi first
#define se second

#define o_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define o_setll tree<ll, null_type,less<ll>, rb_tree_tag,tree_order_statistics_node_update>
//to delete an element
//s.erase(s.find_by_order(s.order_of_key(ele)));
//where s is the name of the ordered_set
//member functions :
//1. order_of_key(k) : number of elements strictly lesser than k
//2. find_by_order(k) : k-th element in the set

using namespace std;
using namespace __gnu_pbds;

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef MY_PROJECT
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

ll powers_of_25[2000010];
ll powers_of_26[2000010];

void preprocess(){
    powers_of_25[0]=1;
    powers_of_26[0]=1;
    for(int i=1;i<=1000000;i++)
    {
        powers_of_25[i]=powers_of_25[i-1]*25ll;
        powers_of_25[i]%=hell;
        powers_of_26[i]=powers_of_26[i-1]*26ll;
        powers_of_26[i]%=hell;
    }
}

inline int fast_expo(int base,int power,int modulo=hell){
    base%=modulo;
    if (base<0) base+=modulo;
    ll x=base,cnt=power,ans=1;
    while(cnt){
        if (cnt&1) ans=(ans*x)%modulo;
        x=(x*x)%modulo;
        cnt>>=1;
    }
    return ans;
}
inline int inv(int base,int modulo=hell){
    return fast_expo(base,modulo-2,modulo);
}

int main()
{
    IOS
    /*
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    */
    preprocess();
    ll ntc=1;
    //cin>>ntc;
    rep(tc,1,ntc+1)
    {
        //cout<<"Case #"<<tc<<": ";
        ll k;
        cin>>k;
        string s;
        cin>>s;
        ll sum=0;
        int ini=s.length();
        ll cur=1;
        for(int i=ini;i<=ini+k;i++)
        {
            if(i!=ini){
                cur=cur*(((ll)(i-1)*(ll)inv(i-ini))%hell);
                cur%=hell;
            }
            sum=sum+(((powers_of_25[i-ini]*powers_of_26[ini+k-i])%hell)*cur)%hell;
            sum%=hell;
        }
        cout<<sum;
    }
    return 0;
}


Measured memory_bytes: 19888