//https://www.infoarena.ro/problema/divk

//#pragma GCC optimize ("Ofast")
//#pragma GCC optimize ("fast-math")
//#pragma GCC optimize ("unroll-loops")
//#define _USE_MATH_DEFINES

#include <iostream>
#include <fstream>
//#include <vector>
//#include <cstring>
//#include <cmath>
//#include <bitset>
//#include <queue>
//#include <stack>
//#include <utility>
//#include <algorithm>
//#include <string>
//#include <map>
//#include <unordered_map>
//#include <set>
//#include <unordered_set>
//#include <cstdint>
//#include <climits>
//#include <iomanip>
//#include <cstdio>
//#include <tuple>

using namespace std;

ifstream fin("divk.in");
ofstream fout("divk.out");

const int NRMAX = 500000;
const int KMAX = 100000;

int64_t sp[NRMAX + 1], fr[KMAX + 1];

int main()
{
    //ios_base::sync_with_stdio(false);
    //cin.tie(NULL);

    int n, k, a, b, i, rez = 0;

    fin >> n >> k >> a >> b;

    for (i = 1; i <= n; ++i)
    {
        int64_t x;
        fin >> x;

        sp[i] = (sp[i - 1] + x) % k;
    }


    for (i = 1; i <= n; ++i)
    {
        // Pozitia pe care adaug i-a
        // Pozitia de pe care scot i-b-1
        //cout << i - a << " " << i - b - 1 << "\n";

        int adg = i - a;
        if (adg >= 1)
            ++fr[sp[adg]];

        int elim = i - b - 1;
        if (elim >= 1)
            --fr[sp[elim]];

        rez += fr[sp[i]];
    }

    fout << rez;

    return 0;
}