#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")
#include <bits/stdc++.h>
#define rep(i,n) for(int i=1;i<=n;++i)
#define pb push_back
#define mp make_pair
using namespace std;
#define N 50010
bitset<N> a[N],b[N];
int n,m,p[N],pos[N];
int main()
{
    cin>>n>>m;
    rep(i,n)scanf("%d",&p[i]);
    rep(i,n)pos[p[i]]=i;
    bitset<N> x; x.reset();
    for(int i=n;i>=1;i--)
    {
        a[pos[i]]=x>>pos[i];
        x[pos[i]]=1;
    }
    long long ans=0;
    x.set();
    b[m]=a[m];
    for(int i=m-1;i>=1;i--)b[i]=b[i+1]&a[i];
    ans+=b[1].count();
    int now=1;
    for(int i=m+1;i<=n;i++)
    {
        x&=a[i];
        if (now%m==0)
        {
            b[i]=a[i];
            for(int j=i-1;j>=i-m+1;j--)b[j]=b[j+1]&a[j];
        }
        now++;
        ans+=(x&b[now]).count();
    }
    cout<<ans<<endl;
    return 0;
}