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

class Program
{
    static long NN => long.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, k) = (c[0], c[1]);
        var a = NList;
        var mod = 1_000_000_007;
        var dp = new long[20001];
        dp[10000] = 1;
        for (var i = 0; i < n; ++i)
        {
            var ndp = (long[]) dp.Clone();
            for (var j = 0; j < dp.Length; ++j)
            {
                var next = a[i] - k + j;
                if (next < 0 || next >= dp.Length) continue;
                ndp[next] = (ndp[next] + dp[j]) % mod;
            }
            dp = ndp;
        }
        var ans = 0L;
        for (var i = 10000; i < dp.Length; ++i) ans = (ans + dp[i]) % mod;
        WriteLine((ans - 1 + mod) % mod);
    }
}