16 #define N 100000+5 17  18 int a[N],dp[N],Ans[N]; 19 struct segment { 20     int l,r; 21     int Min,Max,ans; 22 } seg[4*N]; 23  24 struct diff { 25     int Max,Min; 26     diff(int x=0,int n=0):Max(x),Min(n) {} 27 }; 28  29 void build(int p,int l,int r) 30 { 31     seg[p].l=l, seg[p].r=r, seg[p].ans=-1;; 32     if (l==r) { 33         seg[p].Min = seg[p].Max = a[l]; 34         return; 35     } 36     build(p<<1,l,(l+r)>>1); 37     build((p<<1)+1,((l+r)>>1)+1,r); 38  39     seg[p].Min = min(seg[p<<1].Min, seg[(p<<1)+1].Min), 40     seg[p].Max = max(seg[p<<1].Max, seg[(p<<1)+1].Max); 41 } 42  43 diff query1(int p,int l,int r) 44 { 45     if (l<=seg[p].l && seg[p].r<=r) { 46         return diff(seg[p].Max,seg[p].Min); 47     } 48  49     diff t1,t2; 50     bool f1=false, f2=false; 51     if (seg[p<<1].r>=l) 52         f1=true, t1=query1(p<<1,l,r); 53     if (seg[(p<<1)+1].l<=r) 54         f2=true, t2=query1((p<<1)+1,l,r); 55  56     if (f1) { 57         if (f2) 58             return diff(max(t1.Max,t2.Max), min(t1.Min,t2.Min)); 59         else 60             return t1; 61     } 62     else 63         if (f2) 64             return t2; 65     return diff(0,0); 66 } 67  68 int query2(int p,int l,int r) 69 { 70     if (l<=seg[p].l && seg[p].r<=r) { 71         return seg[p].ans; 72     } 73  74     int t1=-1,t2=-1; 75     if (seg[p<<1].r>=l) 76         t1=query2(p<<1,l,r); 77     if (seg[(p<<1)+1].l<=r) 78         t2=query2((p<<1)+1,l,r); 79  80     if (t1==-1) { 81         return t2; 82     } 83     else { 84         if (t2==-1) 85             return t1; 86         else return min(t1,t2); 87     } 88  89 } 90  91 void add(int p,int i,int newans) 92 { 93     if (seg[p].l==seg[p].r) { 94         seg[p].ans=newans; 95         return; 96     } 97  98     if (i<=seg[p<<1].r) 99         add(p<<1,i,newans);100     else101         add((p<<1)+1,i,newans);102 103     if (seg[p<<1].ans==-1) {104         seg[p].ans = seg[(p<<1)+1].ans;105     }106     else {107         if (seg[(p<<1)+1].ans==-1)108             seg[p].ans=seg[p<<1].ans;109         else110             seg[p].ans=min(seg[p<<1].ans,seg[(p<<1)+1].ans);111     }112 }113 114 int main()115 {116     //freopen("b.txt","r",stdin);117 118     int n,s,l;119     cin>>n>>s>>l;120     for (int i=1;i<=n;i++) scanf("%d",&a[i]);121     build(1,1,n);122     for (int i=1;i<=n;i++) {123         int L=1,R=i-1;124         dp[i]=i;125         while (L<=R) {126             int mid = (L+R)>>1;127             diff tmp = query1(1,mid,i);128             if (tmp.Max-tmp.Min<=s) {129                 R=mid-1;130                 dp[i]=mid;131             }132             else {133                 L=mid+1;134             }135         }136     }137 138 139     for (int i=1;i<=n;i++) {140         if (i<l) {141             Ans[i]=-1;142             continue;143         }144         int tmp=-1;145         if (i-l>0 && dp[i]-1<=i-l)146             tmp=query2(1,max(1,dp[i]-1),i-l);147         if (dp[i]==1) tmp=0;148 149         if (tmp==-1)150             Ans[i]=-1;151         else152             Ans[i]=tmp+1, add(1,i,Ans[i]);153     }154     cout<<Ans[n]<<endl;155 156     return 0;157 }