#include <bits/stdc++.h>
using namespace std;
int main()
{
    int n, a, b;
    cin >> a >> b >> n;
    n += 14;
    int A[34] = {0,990,1010,1970, 2030,2940,5990, 6010,7000};
    int s[34]={0};
    for (int i = 14; i < n; i++)
    {
        cin>>A[i];
    }
    sort(A, A + n);
    s[0] = 1;
    for (int i = 1; i < n; i++)
    {
        for (int j = i - 1; j >= 0 && A[i] - A[j] <= b;j--)
        {
            if (A[i] - A[j] < a)
            {
                continue;
            }
            else 
            {
                s[i] += s[j];
            }
        }
    }
    cout << s[n - 1];
    return 0;
}