#include<bits/stdc++.h>
#define SZ(x) ((int)x.size())
#define UNI(x) sort(ALL(x)),x.resize(unique(ALL(x))-x.begin());
#define GETPOS(c,x) (lower_bound(ALL(c),x)-c.begin())
#define GETpos(c,x) (lower_bound(ALL(c),x)-c.begin())////
#define MST(x,val) memset((x),val,sizeof((x)));
#define ls rt<<1
#define rs rt<<1|1
#define lson rt<<1,l,M
#define rson rt<<1|1,M+1,r
#define PI acos(-1)
#define MM int M=(l+r)>>1;
#define fu(i,r,t) for(int i=r;i<=t;i++)
#define fd(i,r,t) for(int i=r;i>=t;i--)
#define fh(i,be,e) for(int i=head[be];~i;i=e[i].next)
#define fa(i,V) for(auto i:V)
#define far(i,V) for(auto &i:V)
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define int long long
#define endl '\n'
#define lcm(a,b) (a*b)/__gcd(a,b)
#define cp(i,ans) printf("%.if",ans);
#define cpp(i,ans) cout<<setprecision(i)<<fixed<<ans<<endl;
#define ppb pop_back
#define ppf pop_front
#define pb push_back
#define pf push_front
#define pq priority_queue
#define lowbit(x) (x)&(-x)
#define all(V) V.begin(),V.end()
#define ms multiset
#define mod(x) ((x+mo_num)%mo_num)
#define vc vector
#define vct vector<int>
#define out(i) cout<<(i)<<endl;
#define fi first
#define se second
#define fun(i) fu(i,1,n)
#define fut(i) fu(i,1,t)
#define fum(i) fu(i,1,m)
#define ld long double
#define umap unordered_map
#define P pair<int,int>
#define SET set<int>
#define mp map<int,int>
#define mk make_tuple
#define low lower_bound
#define upp upper_bound
#define yn(key) out(key?"YES":"NO")
#define in(i) i+1,i+1+n
#define im(i) i+1,i+1+m
#define bffs(i) __builtin_ffs(i)
#define bcount(i) __builtin_popcount(i)
#define bone(i) ((1<<i)-1)
#define db double
#define got(container,num) get<num-1>(container)
using namespace std;
//Remember cancel"#define endl '\n'" in interactive questions or use "<<flush"
// use C:printf("%.16f", x);  ->  printf("%.10f", x); can accelerate the program
typedef unsigned long long ull; template<class T> void _R(T &x) { cin >> x; }void _R(int32_t &x) { scanf("%d", &x); }void _R(long long &x) { scanf("%lld", &x); }void _R(ull &x) { scanf("%llu", &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 int32_t &x) { printf("%d", x); }void _W(const long long &x) { printf("%lld", x); }void _W(const double &x) { printf("%.16f", x); }void _W(const char &x) { putchar(x); }void _W(const char *x) { printf("%s", x); }template<class T,class U> void _W(const pair<T,U> &x) {_W(x.F); putchar(' '); _W(x.S);}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...); }
const int INF=LLONG_MAX/2,SINF=0x3f3f3f3f,Lim=1<<20,MINF=LLONG_MAX;
const int dx[]={0,0,-1,1},dy[]={-1,1,0,0};//up down left right
const int maxn=2e6+1e5;
const int mo_num=1e9+7;
//const int mo_num=998244353;
int n,m,t,a[maxn],b[maxn],ans;


int jc[maxn];
int ext_gcd(int a,int b,int &x,int &y){ if(b==0){x=1;y=0;return a;}int q=a/b, g=ext_gcd(b,a-q*b,x,y), z=x-q*y;x=y; y=z;return g; }
int inv(int a){ int x,y;ext_gcd(a,mo_num,x,y);return (x+mo_num)%mo_num; }
void init(int *x, int len){ x[0]=1;for(int i=1;i<len;i++)x[i]=(x[i-1]*i)%mo_num; }
int C(int r,int N){ if(N<0 or N<r or r<0)return 0;return (jc[N]*inv(jc[r])%mo_num)*inv(jc[N-r])%mo_num; }
const int N=2e6;
int Pow(int a,int b){//快速幂(取模数版)
    a%=mo_num;
    int ans = 1;
    while(b)
    {
        if(b&1)
            ans = (ans*a)%mo_num;
        a = (a*a)%mo_num;
        b/=2;
    }
    return ans%mo_num;
}

void solve()
{
    cin>>n;
    string k;
    cin>>k;
    m=k.length();
    fu(i,m-1,n+m-1)
    {
        ans=mod(ans+mod(C(m-1,i))*mod(Pow(25,i-m+1)*Pow(26,n-(i-m+1))));
    }
    out(ans)
    return ;
}
main()
{
    IOS
    init(jc,N);
    int T=1;
    //cin>>T;
    while(T--)solve();
    return 0;
}


Measured memory_bytes: 19872