// #pragma GCC optimize(2)
// #pragma G++ optimize(2)
// #pragma comment(linker,"/STACK:102400000,102400000")

#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
typedef unsigned int ui;
typedef unsigned long long ull;
typedef float fl;
typedef long double ld;
typedef pair<int,int> pii;
#if (WIN32) || (WIN64) || (__WIN32) || (__WIN64) || (_WIN32) || (_WIN64) || (WINDOWS)
#define lld "%I64d"
#define llu "%I64u"
#else
#define lld "%lld"
#define llu "%llu"
#endif
#define ui(n) ((unsigned int)(n))
#define LL(n) ((long long)(n))
#define ull(n) ((unsigned long long)(n))
#define fl(n) ((float)(n))
#define ld(n) ((long double)(n))
#define char(n) ((char)(n))
#define Bool(n) ((bool)(n))
#define fixpoint(n) fixed<<setprecision(n)

const int INF=1061109567;
const int NINF=-1044266559;
const LL LINF=4557430888798830399;
const ld eps=1e-15;
#define MOD (1000000007)
#define PI (3.1415926535897932384626433832795028841971)

#define MP make_pair
#define MT make_tuple
#define All(a) (a).begin(),(a).end()
#define pall(a) (a).rbegin(),(a).rend()
#define Log(x,y) log(x)/log(y)
#define SZ(a) ((int)(a).size())
#define rep(i,n) for(int i=0;i<((int)(n));i++)
#define rep1(i,n) for(int i=1;i<=((int)(n));i++)
#define repd(i,n) for(int i=((int)(n))-1;i>=0;i--)
#define repd1(i,n) for(int i=((int)(n));i>=1;i--)
#define repv(itr,v) for(__typeof((v).begin()) itr=(v).begin();itr!=(v).end();itr++)
#define repV(i,v) for(auto i:v)
#define repE(i,v) for(auto &i:v)
#define MS(x,y) memset(x,y,sizeof(x))
#define MC(x) MS(x,0)
#define MINF(x) MS(x,63)
#define MCP(x,y) memcpy(x,y,sizeof(y))
#define UN(v) sort(All(v)),v.erase(unique(All(v)),v.end())
#define filein(x) freopen(x,"r",stdin)
#define fileout(x) freopen(x,"w",stdout)
#define fileio(x)\
	freopen(x".in","r",stdin);\
	freopen(x".out","w",stdout)
#define filein2(filename,name) ifstream name(filename,ios::in)
#define fileout2(filename,name) ofstream name(filename,ios::out)
#define fileio2(filename,name) fstream name(filename,ios::in|ios::out)
#define sqr(x) ((x)*(x))
#define Pause system("pause")
#define Cls system("cls")
#define fs first
#define sc second
#define SF scanf
#define PF printf

inline int Read()
{
	int x=0,w=0;char ch=0;while(!isdigit(ch)){w|=ch=='-';ch=getchar();}while(isdigit(ch))x=(x<<3)+(x<<1)+(ch^48),ch=getchar();
	return w?-x:x;
}
inline void Write(int x){if(x<0)putchar('-'),x=-x;if(x>9)Write(x/10);putchar(x%10+'0');}
inline LL powmod(LL a,LL b){LL res=1;a%=MOD;assert(b>=0);for(;b;b>>=1){if(b&1)res=res*a%MOD;a=a*a%MOD;}return res%MOD;}
inline LL gcdll(LL a,LL b){return b?gcdll(b,a%b):a;}

const int dx[]={0,1,0,-1,1,-1,-1,1};
const int dy[]={1,0,-1,0,-1,-1,1,1};
/************************************************************BEGIN************************************************************/
const int maxn=2000010;

int n,m;
string s;
LL fac[maxn],inv[maxn],ans;

inline LL C(int a,int b)
{
	if(b>a) return 0ll; else return fac[a]*inv[b]%MOD*inv[a-b]%MOD;
}

int main()
{
	fac[0]=fac[1]=1;
	for(int i=2;i<=2000000;i++) fac[i]=fac[i-1]*i%MOD;

	inv[2000000]=powmod(fac[2000000],MOD-2);
	for(int i=2000000-1;i>=0;i--) inv[i]=inv[i+1]*(i+1)%MOD;

	cin>>n>>s;m=SZ(s);

	for(int i=m;i<=n+m;i++) ans=(ans+C(i-1,m-1)*powmod(25,i-m)%MOD*powmod(26,n+m-i)%MOD)%MOD;
	
	cout<<ans;

	return 0;
}
/*************************************************************END**************************************************************/

Measured memory_bytes: 36576