import std;
immutable int letters = 26;
immutable int mod = 10 ^^ 9 + 7;
long powMod (long a, int p) {
	long res = 1;
	for ( ; p; p >>= 1) {
		if (p & 1) {
			res = (res * 1L * a) % mod;
		}
		a = (a * 1L * a) % mod;
	}
	return res;
}
alias invMod = a => powMod (a, mod - 2);
immutable int mult = ((letters - 1L) * invMod (letters)) % mod;
void main () {
	int k;
	while (readf !(" %s") (k) > 0) {
		readln;
	 	auto s = readln.strip;
		auto n = s.length.to !(int);
		auto cur = powMod (letters, k);
		auto res = cur;
		foreach (i; 0..k) {
			cur = (cur * 1L * mult) % mod;
			cur = (cur * 1L * (n + i)) % mod;
			cur = (cur * 1L * invMod (i + 1)) % mod;
			res = (res + cur) % mod;
		}
		writeln (res);
	}
}
