using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using AtCoderLibraryCSharp;

namespace Tasks
{
    public class F
    {
        static void Main(string[] args)
        {
            var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);
            Solve();
            Console.Out.Flush();
        }

        public static void Solve()
        {
            var K = Scanner.Scan<int>();
            var S = Scanner.Scan<string>();
            var N = S.Length;

            var max = K + N + 1;
            var facts = new ModuloInteger[max];
            facts[0] = 1;
            for (var i = 1; i < max; i++) facts[i] = facts[i - 1] * i;

            var factInvs = new ModuloInteger[max];
            factInvs[max - 1] = facts[max - 1].Inverse();
            for (var i = max - 2; i >= 1; i--) factInvs[i] = factInvs[i + 1] * (i + 1);
            factInvs[0] = 1;

            ModuloInteger answer = 0;
            ModuloInteger Combination(int n, int r) => facts[n] * factInvs[r] * factInvs[n - r];
            for (var i = 0; i <= K; i++)
            {
                ModuloInteger comb = Combination(N + K - i - 1, N - 1);
                comb *= (ModuloInteger.Power(25, K - i) * ModuloInteger.Power(26, i));
                answer += comb;
            }
            Console.WriteLine(answer.Value);
        }

        public static class Scanner
        {
            private static Queue<string> queue = new Queue<string>();
            public static T Next<T>()
            {
                if (!queue.Any()) foreach (var item in Console.ReadLine().Trim().Split(" ")) queue.Enqueue(item);
                return (T)Convert.ChangeType(queue.Dequeue(), typeof(T));
            }
            public static T Scan<T>() => Next<T>();
            public static (T1, T2) Scan<T1, T2>() => (Next<T1>(), Next<T2>());
            public static (T1, T2, T3) Scan<T1, T2, T3>() => (Next<T1>(), Next<T2>(), Next<T3>());
            public static (T1, T2, T3, T4) Scan<T1, T2, T3, T4>() => (Next<T1>(), Next<T2>(), Next<T3>(), Next<T4>());
            public static (T1, T2, T3, T4, T5) Scan<T1, T2, T3, T4, T5>() => (Next<T1>(), Next<T2>(), Next<T3>(), Next<T4>(), Next<T5>());
            public static IEnumerable<T> ScanEnumerable<T>() => Console.ReadLine().Trim().Split(" ").Select(x => (T)Convert.ChangeType(x, typeof(T)));
        }
    }
}

namespace AtCoderLibraryCSharp
{
    public readonly struct ModuloInteger
    {
        public long Value { get; }
        // for performance
        public const long Modulo = (long)1e9 + 7;

        public ModuloInteger(long data) => Value = (0 <= data ? data : data + Modulo) % Modulo;
        public static implicit operator long(ModuloInteger mint) => mint.Value;
        public static implicit operator int(ModuloInteger mint) => (int)mint.Value;
        public static implicit operator ModuloInteger(long val) => new ModuloInteger(val);
        public static implicit operator ModuloInteger(int val) => new ModuloInteger(val);
        public static ModuloInteger operator +(ModuloInteger a, ModuloInteger b) => a.Value + b.Value;
        public static ModuloInteger operator +(ModuloInteger a, long b) => a.Value + b;
        public static ModuloInteger operator +(ModuloInteger a, int b) => a.Value + b;
        public static ModuloInteger operator -(ModuloInteger a, ModuloInteger b) => a.Value - b.Value;
        public static ModuloInteger operator -(ModuloInteger a, long b) => a.Value - b;
        public static ModuloInteger operator -(ModuloInteger a, int b) => a.Value - b;
        public static ModuloInteger operator *(ModuloInteger a, ModuloInteger b) => a.Value * b.Value;
        public static ModuloInteger operator *(ModuloInteger a, long b) => a.Value * (b % Modulo);
        public static ModuloInteger operator *(ModuloInteger a, int b) => a.Value * (b % Modulo);
        public static ModuloInteger operator /(ModuloInteger a, ModuloInteger b) => a * b.Inverse();
        public static ModuloInteger operator /(ModuloInteger a, long b) => a.Value * Inverse(b);
        public static ModuloInteger operator /(ModuloInteger a, int b) => a.Value * Inverse(b);
        public static bool operator ==(ModuloInteger a, ModuloInteger b) => a.Value == b.Value;
        public static bool operator !=(ModuloInteger a, ModuloInteger b) => a.Value != b.Value;
        public bool Equals(ModuloInteger other) => Value == other.Value;
        public override bool Equals(object obj) => obj is ModuloInteger other && Equals(other);
        public override int GetHashCode() => Value.GetHashCode();
        public override string ToString() => Value.ToString();

        public ModuloInteger Inverse() => Inverse(Value);

        public static ModuloInteger Inverse(long a)
        {
            if (a == 0) return 0;
            var p = Modulo;
            var (x1, y1, x2, y2) = (1L, 0L, 0L, 1L);
            while (true)
            {
                if (p == 1) return (x2 % Modulo + Modulo) % Modulo;
                var div = a / p;
                x1 -= x2 * div;
                y1 -= y2 * div;
                a %= p;
                if (a == 1) return (x1 % Modulo + Modulo) % Modulo;
                div = p / a;
                x2 -= x1 * div;
                y2 -= y1 * div;
                p %= a;
            }
        }

        public ModuloInteger Power(long n) => Power(Value, n);

        public static ModuloInteger Power(ModuloInteger x, long n)
        {
            if (n < 0) throw new ArgumentException();
            var r = new ModuloInteger(1);
            while (n > 0)
            {
                if ((n & 1) > 0) r *= x;
                x *= x;
                n >>= 1;
            }

            return r;
        }
    }
}


Measured memory_bytes: 63228