#include <bits/stdc++.h>
#define vector basic_string
#define pii array<int,2>
using namespace std;
typedef long long ll;
template<typename type>
inline void read(type &s){
	int f=1;s=0;
	char ch=getchar();
	while(!isdigit(ch)){
		if(ch=='-') f=-1;
		ch=getchar();
	}
	while(isdigit(ch)){
		s=s*10+(ch-'0');
		ch=getchar();
	}
	s*=f;
}
template<typename type,typename ...T>
inline void read(type &x,T&...y){read(x),read(y...);}
inline ll read(){
	ll x;
	read(x);
	return x;
}
bitset<50001>a[50001],tmp;
int n,m,p[50001];
ll ans;
int main(){
	n=read(),m=read();
	for(int i=1;i<=n;i++) p[read()]=i;
	for(int i=1;i<=m;i++){
		tmp.reset();
		for(int j=1;j<=n;j++){
			if(p[j]<i) continue;
			if(i==1) a[p[j]-i+1]=tmp;
			else a[p[j]-i+1]&=tmp;
			tmp.set(p[j]-i+1);
		}
	}
	// for(int i=1;i<=n;i++,puts(""))
		// for(int j=1;j<=n;j++) printf("%lld ",(int)a[i][j]);
	for(int i=1;i<=n-m+1;i++) ans+=a[i].count();
	printf("%lld\n",ans>>1);
	return 0;
}