#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,bmi,fma,popcnt")
#include<bits/stdc++.h>
#define ONLINE
#ifndef ONLINE
char DEBUG_BUFFER[1000];
#define debug(...) {sprintf(DEBUG_BUFFER,##__VA_ARGS__);\
cerr<<"\033[1;36m"<<DEBUG_BUFFER<<"\033[0;2m"<<"\033[0m";}
#else
#define debug(...) ;
#endif
using LL=long long;
using PII=std::pair<int,int>;
#define all(x) (x).begin(),(x).end()
#define allr(x) (x).rbegin(),(x).rend()
#define FAST_IO {std::ios::sync_with_stdio(false);std::cin.tie(nullptr);}
inline int read(){static int x; std::cin>>x; return x;}
#define N 50001
//#define N 6
int main(){
FAST_IO;
int n=read(),m=read();
std::vector<int>pos(n);
for(int i=0;i<n;i++){
pos[read()-1]=i;
}
std::vector<std::bitset<N>>f(n),suf(m);
std::bitset<N>tmp; tmp.reset();
for(int x=n-1;x>=0;x--){
f[pos[x]]=tmp>>pos[x];
tmp[pos[x]]=1;
}
#ifndef ONLINE
for(int i=0;i<n;i++){
debug("f[%d]=",i+1);
cerr<<f[i]<<"\n";
}
#endif
LL ans=0;
for(int i=0,last=-1;i<n-m+1;i++){
if(i>last){
last+=m;
suf[0]=f[last];
for(int j=1;j<m;j++){
suf[j]=suf[j-1]&f[last-j];
}
#ifndef ONLINE
debug("update suf\n");
debug("\tlast=%d\n",last);
for(int j=0;j<m;j++){
debug("suf[%d]=",j+1);
cerr<<suf[j]<<"\n";
}
#endif
tmp.set();
}
ans+=(suf[last-i]&tmp).count();
tmp&=f[i+m];
}
std::cout<<ans;
return 0;
}
/* stuff you should look for
* int overflow, array bounds
* special cases (n=1?)
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH
*/