#include <fstream>
#include <deque>
using namespace std;
ifstream fin("divk.in");
ofstream fout("divk.out");


int n,k,a,b;

const int kmax = 100000;

int f[kmax + 5];

deque <long long> q;
long long sol;

int main()
{
    fin>>n>>k>>a>>b;
    for(int i=1;i<=n;i++)
    {
        int x;
        fin>>x;
        if(i>k)
            f[q.front()--],q.pop_front();
        int elem=x%k;
        if(!q.empty())
            elem=(elem + q.back())%k;
        q.push_back(elem);
        sol += f[elem];
        f[elem]++;
    }
    fout<<sol;
}