#include <bits/stdc++.h>

#define ll long long
#define pb push_back
#define f first
#define s second
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define ios ios_base::sync_with_stdio(false);cin.tie(NULL)
#define ld long double
#define li __int128

using namespace std;

mt19937 rng(time(NULL));

const int N=5;
int main()
{
	// 9:47
	// 9:57 done coding, but not correct
	ios;
	int n,m;
	cin >> n >> m;
	vector<int> ord(n);
	bitset<N> on;
	vector<bitset<N>> my(n),pr(n),sf(n);
	for(int i=0;i<n;i++){
		int x;
		cin >> x;
		ord[x-1]=i;
	}
	for(int i=n-1;i>=0;i--){
		my[ord[i]]=on>>ord[i];
		on[ord[i]]=1;
	}
	for(int i=0;i<n;i++){
		if(i%m==0){
			pr[i]=my[i];
		}
		else{
			pr[i]=pr[i-1]&my[i];
		}
	}
	for(int i=n-1;i>=0;i--){
		if(i==n-1||((i-1)%m==0)){
			sf[i]=my[i];
		}
		else{
			sf[i]=sf[i+1]&my[i];
		}
	}
	ll ans=0;
	int c=1;
	for(int i=0;i<=n-m;i++){
		c--;
		if(c==0){
			ans+=sf[i].count();
			c=m;
			continue;
		}
		ans+=(sf[i]&pr[i+m-1]).count();
	}
	printf("%lld\n",ans);
	return 0;
}