#include <bits/stdc++.h>
using namespace std;
using ll = int_fast64_t;
const int mod = 1e9 + 7;
const int inf = (1 << 30) - 1;
const ll infll = (1LL << 61) - 1;
#define fast() ios::sync_with_stdio(false), cin.tie(nullptr)
#define digit(N) cout << fixed << setprecision((N))
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

template <typename A, typename B>
string to_string(pair<A, B> p);

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);

string to_string(const string &s)
{
	return '"' + s + '"';
}

string to_string(const char *s)
{
	return to_string((string)s);
}

string to_string(bool b)
{
	return (b ? "true" : "false");
}

string to_string(vector<bool> v)
{
	bool first = true;
	string res = "{";
	for (int i = 0; i < static_cast<int>(v.size()); i++)
	{
		if (!first)
		{
			res += ", ";
		}
		first = false;
		res += to_string(v[i]);
	}
	res += "}";
	return res;
}

template <size_t N>
string to_string(bitset<N> v)
{
	string res = "";
	for (size_t i = 0; i < N; i++)
	{
		res += static_cast<char>('0' + v[i]);
	}
	return res;
}

template <typename A>
string to_string(A v)
{
	bool first = true;
	string res = "{";
	for (const auto &x : v)
	{
		if (!first)
		{
			res += ", ";
		}
		first = false;
		res += to_string(x);
	}
	res += "}";
	return res;
}

template <typename A, typename B>
string to_string(pair<A, B> p)
{
	return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p)
{
	return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p)
{
	return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T)
{
	cerr << " " << to_string(H);
	debug_out(T...);
}

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

const int mod1 = 1e9 + 7;
const int mod2 = 998244353;
struct Combination
{
	using ll = int_fast64_t;

	int mod;
	vector<ll> mfact, rfact;

	Combination(int sz, int mod) : mfact(sz + 1), rfact(sz + 1), mod(mod)
	{
		mfact[0] = 1LL;
		for (int i = 1; i < sz + 1; i++)
		{
			mfact[i] = mfact[i - 1] * i % mod;
		}

		rfact[sz] = inv(mfact[sz]);

		for (int i = sz - 1; i >= 0; i--)
		{
			rfact[i] = rfact[i + 1] * (i + 1) % mod;
		}
	}

	ll fact(int k) const
	{
		return mfact[k];
	}

	ll pow(ll x, ll n) const
	{
		ll ret = 1LL;
		while (n > 0)
		{
			if (n & 1)
				(ret *= x) %= mod;
			(x *= x) %= mod, n >>= 1;
		}
		return ret;
	}

	ll inv(ll x) const
	{
		return pow(x, mod - 2);
	}

	ll Perm(int n, int r) const
	{
		if (r < 0 || n < r)
			return 0LL;
		return mfact[n] * rfact[n - r] % mod;
	}

	ll Binom(int p, int q) const
	{
		if (q < 0 || p < q)
			return 0LL;
		return mfact[p] * rfact[q] % mod * rfact[p - q] % mod;
	}
};

int main()
{
	int K;
	string s;
	cin >> K >> s;

	ll ans = 0, N = s.size();

	Combination Comb(N + K, mod1);
	for (int i = 0; i <= K; i++)
	{
		ans += (Comb.pow(26, K - i) * Comb.pow(25, i) % mod1) * Comb.Binom(i + N - 1, N - 1);
		ans %= mod1;
	}

	cout << ans << "\n";
}

Measured memory_bytes: 35632