import java.util.Scanner;

public class Guliguli {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        int n = in.nextInt();
        int s = in.nextInt();

        long[] times = new long[n];
        long answ = 0;
        for (int i = 0; i < n; i++) {
            long curTime = i + s * in.nextInt();
            int pos = i;
            while(pos > 0 && times[pos] > curTime) {
                times[pos + 1] = times[pos];
                pos--;
                answ++;
            }
            times[pos] = curTime;
        }

        System.out.println(answ);
    }
}