#include <iostream>
#include <fstream>
using namespace std;

const int N=500000;
const int K=100000;
int n,a,b,k;
int s[N],f[K];
long temp;
int secv;

int main()
{
    ifstream in("divk.in");
    ofstream out("divk.out");
    in>>n>>k>>a>>b;
    for(int i=1;i<=n;i++)
    {
        in>>temp;
        temp%=k;
        s[i]=(s[i-1]+temp)%k;
        secv+=f[s[i]];
        f[s[i]]++;
        if(s[i-b+1]==s[i])
            f[s[i]]--;
    }
    out<<secv;
    return 0;
}