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

template<typename T>
struct Z_p{
	using Type = typename decay<decltype(T::value)>::type;
	constexpr Z_p(): value(){ }
	template<typename U> Z_p(const U &x){ value = normalize(x); }
	template<typename U> static Type normalize(const U &x){
		Type v;
		if(-mod() <= x && x < mod()) v = static_cast<Type>(x);
		else v = static_cast<Type>(x % mod());
		if(v < 0) v += mod();
		return v;
	}
	const Type& operator()() const{ return value; }
	template<typename U> explicit operator U() const{ return static_cast<U>(value); }
	constexpr static Type mod(){ return T::value; }
	Z_p &operator+=(const Z_p &otr){ if((value += otr.value) >= mod()) value -= mod(); return *this; }
	Z_p &operator-=(const Z_p &otr){ if((value -= otr.value) < 0) value += mod(); return *this; }
	template<typename U> Z_p &operator+=(const U &otr){ return *this += Z_p(otr); }
	template<typename U> Z_p &operator-=(const U &otr){ return *this -= Z_p(otr); }
	Z_p &operator++(){ return *this += 1; }
	Z_p &operator--(){ return *this -= 1; }
	Z_p operator++(int){ Z_p result(*this); *this += 1; return result; }
	Z_p operator--(int){ Z_p result(*this); *this -= 1; return result; }
	Z_p operator-() const{ return Z_p(-value); }
	template<typename U = T>
	typename enable_if<is_same<typename Z_p<U>::Type, int>::value, Z_p>::type& operator*=(const Z_p& rhs){
		#ifdef _WIN32
		uint64_t x = static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value);
		uint32_t xh = static_cast<uint32_t>(x >> 32), xl = static_cast<uint32_t>(x), d, m;
		asm(
			"divl %4; \n\t"
			: "=a" (d), "=d" (m)
			: "d" (xh), "a" (xl), "r" (mod())
		);
		value = m;
		#else
		value = normalize(static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value));
		#endif
		return *this;
	}
	template<typename U = T>
	typename enable_if<is_same<typename Z_p<U>::Type, int64_t>::value, Z_p>::type& operator*=(const Z_p &rhs){
		int64_t q = static_cast<int64_t>(static_cast<long double>(value) * rhs.value / mod());
		value = normalize(value * rhs.value - q * mod());
		return *this;
	}
	template<typename U = T>
	typename enable_if<!is_integral<typename Z_p<U>::Type>::value, Z_p>::type& operator*=(const Z_p &rhs){
		value = normalize(value * rhs.value);
		return *this;
	}
	Z_p operator^(long long e) const{
		Z_p b = *this, res = 1;
		if(e < 0) b = 1 / b, e = -e;
		for(; e; b *= b, e >>= 1) if(e & 1) res *= b;
		return res;
	}
	Z_p &operator^=(const long long &e){ return *this = *this ^ e; }
	Z_p &operator/=(const Z_p &otr){
		Type a = otr.value, m = mod(), u = 0, v = 1;
		while(a){
			Type t = m / a;
			m -= t * a; swap(a, m);
			u -= t * v; swap(u, v);
		}
		assert(m == 1);
		return *this *= u;
	}
	template<typename U> friend const Z_p<U> &abs(const Z_p<U> &v){ return v; }
	template<typename U> friend bool operator==(const Z_p<U> &lhs, const Z_p<U> &rhs);
	template<typename U> friend bool operator<(const Z_p<U> &lhs, const Z_p<U> &rhs);
	template<typename U> friend istream &operator>>(istream &in, Z_p<U> &number);
	Type value;
};
template<typename T> bool operator==(const Z_p<T> &lhs, const Z_p<T> &rhs){ return lhs.value == rhs.value; }
template<typename T, typename U> bool operator==(const Z_p<T>& lhs, U rhs){ return lhs == Z_p<T>(rhs); }
template<typename T, typename U> bool operator==(U lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) == rhs; }
template<typename T> bool operator!=(const Z_p<T> &lhs, const Z_p<T> &rhs){ return !(lhs == rhs); }
template<typename T, typename U> bool operator!=(const Z_p<T> &lhs, U rhs){ return !(lhs == rhs); }
template<typename T, typename U> bool operator!=(U lhs, const Z_p<T> &rhs){ return !(lhs == rhs); }
template<typename T> bool operator<(const Z_p<T> &lhs, const Z_p<T> &rhs){ return lhs.value < rhs.value; }
template<typename T> Z_p<T> operator+(const Z_p<T> &lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) += rhs; }
template<typename T, typename U> Z_p<T> operator+(const Z_p<T> &lhs, U rhs){ return Z_p<T>(lhs) += rhs; }
template<typename T, typename U> Z_p<T> operator+(U lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) += rhs; }
template<typename T> Z_p<T> operator-(const Z_p<T> &lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) -= rhs; }
template<typename T, typename U> Z_p<T> operator-(const Z_p<T>& lhs, U rhs){ return Z_p<T>(lhs) -= rhs; }
template<typename T, typename U> Z_p<T> operator-(U lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) -= rhs; }
template<typename T> Z_p<T> operator*(const Z_p<T> &lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) *= rhs; }
template<typename T, typename U> Z_p<T> operator*(const Z_p<T>& lhs, U rhs){ return Z_p<T>(lhs) *= rhs; }
template<typename T, typename U> Z_p<T> operator*(U lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) *= rhs; }
template<typename T> Z_p<T> operator/(const Z_p<T> &lhs, const Z_p<T> &rhs) { return Z_p<T>(lhs) /= rhs; }
template<typename T, typename U> Z_p<T> operator/(const Z_p<T>& lhs, U rhs) { return Z_p<T>(lhs) /= rhs; }
template<typename T, typename U> Z_p<T> operator/(U lhs, const Z_p<T> &rhs) { return Z_p<T>(lhs) /= rhs; }
template<typename T> istream &operator>>(istream &in, Z_p<T> &number){
	typename common_type<typename Z_p<T>::Type, int64_t>::type x;
	in >> x;
	number.value = Z_p<T>::normalize(x);
	return in;
}
template<typename T> ostream &operator<<(ostream &out, const Z_p<T> &number){ return out << number(); }

/*
using ModType = int;
struct VarMod{ static ModType value; };
ModType VarMod::value;
ModType &mod = VarMod::value;
using Zp = Z_p<VarMod>;
*/

constexpr int mod = (int)1e9 + 7;
//constexpr int mod = 998244353;
using Zp = Z_p<integral_constant<decay<decltype(mod)>::type, mod>>;

template<int SZ, typename Zp>
struct combinatorics{
	vector<Zp> inv, fact, invfact;
	vector<vector<Zp>> stir1, stir2;
	combinatorics(): inv(SZ << 1 | 1, 1), fact(SZ << 1 | 1, 1), invfact(SZ << 1 | 1, 1){
		for(int i = 1; i <= SZ << 1; ++ i) fact[i] = fact[i - 1] * i;
		invfact[SZ << 1] = 1 / fact[SZ << 1];
		for(int i = (SZ << 1) - 1; i >= 0; -- i){
			invfact[i] = invfact[i + 1] * (i + 1);
			inv[i + 1] = invfact[i + 1] * fact[i];
		}
	}
	Zp C(int n, int k){ return n < k ? 0 : fact[n] * invfact[k] * invfact[n - k]; }
	Zp P(int n, int k){ return n < k ? 0 : fact[n] * invfact[n - k]; }
	Zp H(int n, int k){ return C(n + k - 1, k); }
	vector<Zp> precalc_power(int base){
		vector<Zp> res(SZ << 1 | 1, 1);
		for(auto i = 1; i <= SZ << 1; ++ i) res[i] = res[i - 1] * base;
		return res;
	}
	Zp naive_C(long long n, long long k){
		if(n < k) return 0;
		Zp res = 1;
		k = min(k, n - k);
		for(int i = n; i > n - k; -- i) res *= i;
		return res * invfact[k];
	}
	Zp naive_P(long long n, int k){
		if(n < k) return 0;
		Zp res = 1;
		for(int i = n; i > n - k; -- i) res *= i;
		return res;
	}
	Zp naive_H(long long n, long long k){ return naive_C(n + k - 1, k); }
	bool parity_C(long long n, long long k){ return n < k ? 0 : k & n - k ^ 1; }
	// Catalan's Trapzoids
	// # of bitstrings of n Xs and k Ys such that in each initial segment, (# of X) + m > (# of Y) 
	Zp Cat(int n, int k, int m = 1){
		if(m <= 0) return 0;
		else if(k >= 0 && k < m) return C(n + k, k);
		else if(k < n + m) return C(n + k, k) - C(n + k, k - m);
		else return 0;
	}
	// Stirling number
	// First kind (unsigned): # of n-permutations with k disjoint cycles
	//                        Also the coefficient of x^k for x_n = x(x+1)...(x+n-1)
	// Second kind: # of ways to partition a set of size n into r non-empty sets
	//              Satisfies sum{k=0~n}(x_k) = x^n
	array<bool, 2> pre{};
	template<bool FIRST = true>
	void precalc_stir(int n, int k){
		auto &s = FIRST ? stir1 : stir2;
		pre[!FIRST] = true;
		s.resize(n + 1, vector<Zp>(k + 1, 1));
		for(int i = 1; i <= n; ++ i) for(int j = 1; j <= k; ++ j){
			s[i][j] = (FIRST ? i - 1 : j) * s[i - 1][j] + s[i - 1][j - 1];
		}
	}
	// unsigned
	Zp Stir1(int n, int k){
		if(n < k) return 0;
		assert(pre[0]);
		return stir1[n][k];
	}
	Zp Stir2(long long n, int k){
		if(n < k) return 0;
		if(pre[1] && n < int(stir2.size())) return stir2[n][k];
		Zp res = 0;
		for(int i = 0, sign = 1; i <= k; ++ i, sign *= -1) res += sign * C(k, i) * (Zp(k - i) ^ n);
		return res * invfact[k];
	}
	bool parity_Stir2(long long n, long long k){ return n < k ? 0 : k ? !(n - k & k - 1 >> 1) : 0; }
};

int main(){
	cin.tie(0)->sync_with_stdio(0);
	const int mx = 1e6;
	combinatorics<mx, Zp> C;
	auto p25 = C.precalc_power(25), p26 = C.precalc_power(26);
	int k;
	string s;
	cin >> k >> s;
	int n = int(s.size());
	Zp res = 0;
	for(auto x = 0; x <= k; ++ x){
		res += p26[x] * p25[k - x] * C.H(n, k - x);
	}
	cout << res;
	return 0;
}

/*

*/

////////////////////////////////////////////////////////////////////////////////////////
//                                                                                    //
//                                   Coded by Aeren                                   //
//                                                                                    //
////////////////////////////////////////////////////////////////////////////////////////

Measured memory_bytes: 43336