#include <iostream>
#include <cstdio>
using namespace std;
const int MAXN = 1e5 + 5;
const int MAXN_LOG = 30;
int logN[MAXN] = {0}, pw[MAXN_LOG] = {0}, a[MAXN] = {0}, n, L, S;
int st_mn[MAXN][MAXN_LOG] = {{0}};
int st_mx[MAXN][MAXN_LOG] = {{0}};
int st_dp[MAXN][MAXN_LOG] = {{0}};
void init() {
	logN[1] = 0;
	for (int i = 2; i <= n; i++)
		logN[i] = logN[i / 2] + 1;
	for (int i = 0; i <= 20; i++)
		pw[i] = (1 << i); 
	for (int i = 1; i <= n; i++)
		st_mn[i][0] = st_mx[i][0] = a[i];
	for (int j = 1; pw[j] <= n; j++)
		for (int i = 1; i + pw[j] - 1 <= n; i++) {
			st_mn[i][j] = min(st_mn[i][j - 1], st_mn[i + pw[j - 1]][j - 1]);
			st_mx[i][j] = max(st_mx[i][j - 1], st_mx[i + pw[j - 1]][j - 1]);
		}
} 
int QryMx(int l, int r) {
	if (l > r)return -2e9;
	int k = logN[r - l + 1];
	return max(st_mx[l][k], st_mx[r - pw[k] + 1][k]);
}
int QryMn(int l, int r) {
	if (l > r)return 2e9;
	int k = logN[r - l + 1];
	return min(st_mn[l][k], st_mn[r - pw[k] + 1][k]);	
}
int QryDif(int l, int r) {
	if (l > r)return 2e9;
	return QryMx(l, r) - QryMn(l, r);
}
int QryDp(int l, int r) {
	if (l > r)return 2e9;
	int k = logN[r - l + 1];
	return min(st_dp[l][k], st_dp[r - pw[k] + 1][k]);
}
void add(int x, int l) {
	for (int k = 0; pw[k] <= l; k++)
		st_dp[l - pw[k] + 1][k] = min(QryDp(l - pw[k] + 1, l - 1), x);
}
int dp[MAXN] = {0};
int main() {
	scanf("%d%d%d", &n, &S, &L);
	for (int i = 1; i <= n; i++)
		scanf("%d", &a[i]);
	init();
	dp[0] = 0;
	int cur = 0;
	for (int i = 1; i <= n; i++) {
		while (i - L >= cur && (QryDif(cur + 1, i) > S || dp[cur] == 2e9))
			cur++;
		if (dp[cur] == 2e9 || QryDp(cur, i - L) == 2e9)
			dp[i] = 2e9;
		else 
			dp[i] = QryDp(cur, i - L) + 1;
		add(dp[i], i);
	}
	printf("%d\n", (dp[n] == 2e9 ? -1 : dp[n]));
	return 0;
}