CHEFTOWN(EASY)

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll; 
ll minimum(ll a, ll b){
    if(a>b)return b;
    else return a;
}
ll maximum(ll a ,ll b){
    if(a>b)return a;
    else return b;
}
struct node{
    ll max;
    ll min;
};
node n={-1,1000000009};  
void printnode(node s){
    cout<<"MIN="<<s.min<<" MAX="<<s.max<<'\n';
}
void build(ll A[],node seg[] ,ll low,  ll high, ll pos){
    if(low==high){
        seg[pos].min=A[low];
        seg[pos].max=A[low];
        //cout<<"Node inserted at "<<pos<<'\n';
        //printnode(seg[pos]);
        return ;
    }
    ll mid = (low+high)/2;
    build(A,seg,low, mid, 2*pos+1);
    build(A,seg,mid+1, high, 2*pos+2);
    seg[pos].min=minimum(seg[pos*2+1].min,seg[pos*2+2].min);
    seg[pos].max=maximum(seg[pos*2+1].max,seg[pos*2+2].max);
    //cout<<"Node inserted at "<<pos<<'\n';
      //  printnode(seg[pos]);
}
node query(node seg[],ll low,ll high,ll qlow, ll qhigh,ll pos ){
    if(qlow>high||qhigh<low||low>high)return n;
    else if(qlow<=low&&qhigh>=high)return seg[pos];
    ll mid=(low+high)/2;
    node res; 
    node r1=query(seg,low,mid,qlow ,qhigh,2*pos+1);
    node r2=query(seg,mid+1,high,qlow ,qhigh,2*pos+2);
    res.max=maximum(r1.max,r2.max);
    res.min=minimum(r1.min,r2.min);
    return res;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    ll N,W;
    cin>>N>>W;
    ll A[N];
    ll x=pow(2,1+ceil(log2(N+1)));
    node seg[x];
    for(int i=0;i<N;i++)cin>>A[i];
    build(A,seg,0,N-1,0);
    ll Ans=0;
    for(int i=0;i<N-W+1;i++){
        node ans=query(seg,0,N-1,i,i+W-1,0);
        //printnode(ans);
        if(ans.max-ans.min+1==W)Ans++;
    }
    cout<<Ans;
	return 0;
}