using System;
using System.Collections.Generic;
using static System.Console;
using System.Linq;

class yuki302
{
    static void Main()
    {
        var a = int.Parse(ReadLine());
        var b = ReadLine().ToCharArray().Select(c => c - '0').ToArray();

        var key = 1000000007;
        var less = new long[a][];
        for (var i = 0; i < a; ++i) less[i] = new long[b.Length];

        var equal = b.Length - 1;
        for (var c = 1; c < b[0]; ++c) less[c][0] = b.Length - 1;
        for (var i = 1; i < b.Length; ++i)
        {
            for (var c = 0; c < a; ++c) for (var pc = 0; pc < a; ++pc) less[c][i] = (less[c][i] + less[pc][i - 1]) % key;
            for (var c = 1; c < a; ++c) less[c][i] = (less[c][i] + b.Length - i - 1) % key;
            for (var c = 0; c < b[i]; ++c) less[c][i] = (less[c][i] + equal) % key;
        }
        var res = 0L;
        for (var c = 0; c < less.Length; ++c) res = (res + less[c].Last()) % key;
        res = (res + equal) % key;
        WriteLine(res);
    }
}