#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline bool maxit(T& a, const T& b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T>
inline bool minit(T& a, const T& b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
inline long long gint() {
  char c = getchar();
  int f = 1;
  while (c < '0' || c > '9') {
    if (c == '-') {
      f = -1;
    }
    c = getchar();
  }
  long long a = c - '0';
  while ((c = getchar()) >= '0' && c <= '9') {
    a = a * 10 + c - '0';
  }
  return a * f;
}
const int maxn = 100010, INF = 0x3f3f3f3f;
pair<int, int> d[maxn][20];
inline pair<int, int> merge(const pair<int, int>& a, const pair<int, int>& b) {
  return make_pair(max(a.first, b.first), min(a.second, b.second));
}
int lg[maxn];
pair<int, int> RMQ(int l, int r) {
  int k = lg[r - l + 1];
  return merge(d[l][k], d[r - (1 << k) + 1][k]);
}
deque<int> dq;
int f[maxn];
int n, s, l;
int main() {
  n = gint();
  s = gint();
  l = gint();
  lg[0] = -1;
  for (int i = 1; i <= n; i++) {
    d[i][0].first = d[i][0].second = gint();
    lg[i] = lg[i >> 1] + 1;
  }
  for (int j = 1; (1 << j) <= n; j++) {
    for (int i = 1; i + (1 << j) - 1 <= n; i++) {
      d[i][j] = merge(d[i][j - 1], d[i + (1 << (j - 1))][j - 1]);
    }
  }
  for (int i = 1, j = 1; i <= n; i++) {
    for (;;) {
      pair<int, int> tmp = RMQ(j, i);
      if (tmp.first - tmp.second <= s) {
        break;
      }
      j++;
    }
    if (i >= l) {
      while (!dq.empty() && f[dq.back()] >= f[i - l]) {
        dq.pop_back();
      }
      dq.push_back(i - l);
    }
    while (!dq.empty() && dq.front() < j - 1) {
      dq.pop_front();
    }
    if (dq.empty()) {
      f[i] = INF;
    } else {
      f[i] = f[dq.front()] + 1;
    }
  }
  if (f[n] > n) {
    puts("-1");
  } else {
    printf("%d\n", f[n]);
  }
  return 0;
}
