#include <bits/stdc++.h>
using namespace std;
int n, s, len;
int h[100005];
int dpmax[100005][20];
int dpmin[100005][20];
int mm[100005];
void init() {
  mm[0] = -1;
  for (int i = 1; i < 100005; i++) {
    if ((i & (i - 1)) == 0)
      mm[i] = mm[i - 1] + 1;
    else
      mm[i] = mm[i - 1];
  }
  for (int i = 0; i < 20; i++)
    for (int j = 0; j < n; j++) {
      if (i == 0) {
        dpmax[j][i] = h[j];
        dpmin[j][i] = h[j];
      } else if (j + (1 << i) - 1 < n) {
        dpmax[j][i] = max(dpmax[j][i - 1], dpmax[j + (1 << (i - 1))][i - 1]);
        dpmin[j][i] = min(dpmin[j][i - 1], dpmin[j + (1 << (i - 1))][i - 1]);
      }
    }
}
int query(int l, int r, int type) {
  int two = mm[r - l + 1];
  if (type)
    return max(dpmax[l][two], dpmax[r - (1 << two) + 1][two]);
  else
    return min(dpmin[l][two], dpmin[r - (1 << two) + 1][two]);
}
int l[100005];
int Q[100005];
int dp[100005];
int main() {
  scanf("%d%d%d", &n, &s, &len);
  for (int i = 0; i < n; i++) scanf("%d", &h[i]);
  init();
  int head = 0;
  for (int i = 0; i < n; i++) {
    while (head < i && (query(head, i, 1) - query(head, i, 0)) > s) head++;
    l[i] = head;
  }
  head = 0;
  int tail = 0;
  if (len > n || l[len - 1] != 0) {
    puts("-1");
    return 0;
  }
  memset(dp, -1, sizeof(dp));
  dp[len - 1] = 1;
  for (int i = len; i < n; i++) {
    if (dp[i - 1] != -1) {
      while (head < tail && dp[Q[tail - 1] - 1] > dp[i - 1]) tail--;
      Q[tail++] = i;
    }
    if (l[i] == 0)
      dp[i] = 1;
    else {
      while (head < tail && !(Q[head] >= l[i])) head++;
      if (head < tail && Q[head] <= i - len + 1) dp[i] = dp[Q[head] - 1] + 1;
    }
  }
  printf("%d\n", dp[n - 1]);
  return 0;
}
