/*

    Author of solution {

           gskhirtladze;

    }

*/

#include <iostream>
#include <stdio.h>
#include <math.h>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
#include <queue>
#include <string>

#define fi first
#define se second
#define pb push_back
#define mk make_pair
#define Pii pair < int , int >
#define tree int t,int l,int r
#define left 2*t,l,(l+r)/2
#define right 2*t+1,(l+r)/2+1,r
#define f_sum(i,r) for (int i=r;i>=0;i=(i&(i+1))-1)
#define f_upd(i,a,r) for (int i=a;i<=r;i=(i|(i+1)))
#define MA(a,b) ((a)>(b)?(a):(b))
#define MI(a,b) ((a)<(b)?(a):(b))
#define AB(a) (-(a)<(a)?(a):-(a))
#define ged(x) scanf("%I64d",&x)
#define getcx getchar//_unlocked
#define put(x) cout<<x<<endl;
#define pud(x) printf("%.12f\n",x);
#define LL long long
#define INF 1000000000
#define eps 0.00000001
#define P7 1000000007
#define P9 1000000009
#define N3 2555
#define N5 262145

using namespace std;

inline void inp(int &n )
 {n=0; int ch=getcx();int sign=1;
  while(ch<'0'||ch>'9'){if(ch=='-')sign=-1; ch=getcx();}
  while(  ch >= '0' && ch <= '9' ) n=(n<<3)+(n<<1)+ch-'0',ch=getcx();
  n=n*sign;}


int tst;
void get_ready() {
     //freopen(".in","r",stdin);
     //freopen(".out","w",stdout);
     tst=1; //inp(tst);
}

int mi[N5],ma[N5],tr[N5],ans[N5],a[N5],la,mii,maa;

void build (tree)
 {
  if (l == r)
  {
   ma[t]=a[l];
   mi[t]=a[l];
   return ;
  }
  build (left);
  build (right);
  ma[t]=MA(ma[2*t],ma[2*t+1]);
  mi[t]=MI(mi[2*t],mi[2*t+1]);
 }

void get_mi(tree,int L,int R)
 {
  if (l > R || L > r) return;
  if (L <= l && r <= R) { la=MI(la,tr[t]); return; }
  get_mi(left,L,R);
  get_mi(right,L,R);
 }

void get_m(tree,int L,int R)
 {
  if (l > R || L > r) return;
  if (L <= l && r <= R) { mii=MI(mii,mi[t]); maa=MA(maa,ma[t]); return; }
  get_m(left,L,R);
  get_m(right,L,R);
 }

void upd_mi(tree,int i,int la)
 {
  if (l > i || i > r) return;
  if (l == r) { tr[t]=la; return; }
  upd_mi(left,i,la);
  upd_mi(right,i,la);
  tr[t]=MI(tr[2*t],tr[2*t+1]);
 }

int n,s,L,i;

main()
 {
 cin>>n>>s>>L;
for (i=1;i<=n;i++)
     cin>>a[i];
 build(1,1,n);
 for (i=1;i<=n;i++)
  {
   int l=1,r=i,m=0,mid=-1;
   while (l <= r)
    {
     m=(l+r)/2;
     mii=INF;
     maa=-INF;
     get_m(1,1,n,m,i);
     if (maa-mii <= s) { mid=m; r=m-1; } else l=m+1;
    }
   mid=mid-1;
   la=INF;
   get_mi(1,0,n,mid,i-L);
   upd_mi(1,0,n,i,la+1);
   ans[i]=la+1;
  }
if (ans[n] >= INF) ans[n]=-1;
cout<<ans[n]<<endl;
 }