#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
int n, s, l, a[N], mx[N][20], mi[N][20];
int t[N << 2];
void _insert(int u, int L, int R, int x, int val) {
  if (L == R) {
    t[u] = val;
    return;
  }
  int mid = (L + R) / 2;
  if (x <= mid)
    _insert((u << 1), L, mid, x, val);
  else
    _insert((u << 1 | 1), mid + 1, R, x, val);
  t[u] = min(t[(u << 1)], t[(u << 1 | 1)]);
}
int query(int u, int L, int R, int ql, int qr) {
  if (L == ql && R == qr) return t[u];
  int mid = (L + R) / 2;
  if (qr <= mid)
    return query((u << 1), L, mid, ql, qr);
  else if (ql > mid)
    return query((u << 1 | 1), mid + 1, R, ql, qr);
  else
    return min(query((u << 1), L, mid, ql, mid),
               query((u << 1 | 1), mid + 1, R, mid + 1, qr));
}
int ask(int L, int R) {
  int lg = log(R - L + 1) / log(2);
  return max(mx[L][lg], mx[R - (1 << lg) + 1][lg]) -
         min(mi[L][lg], mi[R - (1 << lg) + 1][lg]);
}
int _getL(int u) {
  int L = 2, R = u + 1;
  while (L < R) {
    int mid = (L + R) / 2;
    if (ask(mid, u) > s)
      L = mid + 1;
    else
      R = mid;
  }
  return L;
}
int main() {
  scanf("%d %d %d", &n, &s, &l);
  for (int i = 2; i <= n + 1; i++) scanf("%d", &a[i]);
  for (int i = 2; i <= n + 1; i++) mx[i][0] = mi[i][0] = a[i];
  for (int i = 1; (1 << i) <= n; i++) {
    for (int j = 2; j + (1 << i) - 1 <= n + 1; j++) {
      mx[j][i] = max(mx[j][i - 1], mx[j + (1 << (i - 1))][i - 1]);
      mi[j][i] = min(mi[j][i - 1], mi[j + (1 << (i - 1))][i - 1]);
    }
  }
  for (int i = 2; i <= n + 1; i++) {
    int L = _getL(i), R = i - l;
    L--;
    if (L > R)
      _insert(1, 1, n + 1, i, 0x3f3f3f3f);
    else {
      int cur = query(1, 1, n + 1, L, R);
      int val = cur < 0x3f3f3f3f ? cur + 1 : 0x3f3f3f3f;
      _insert(1, 1, n + 1, i, val);
    }
  }
  int val = query(1, 1, n + 1, n + 1, n + 1);
  printf("%d\n", val < 0x3f3f3f3f ? val : -1);
  return 0;
}
