#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace::std;
//struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}} __init;
__attribute__((constructor))
void init(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout<<fixed<<setprecision(15);
}
// random_device rd;
// mt19937 mt(rd());
// #include <boost/numeric/interval.hpp>
// #include <boost/numeric/interval/io.hpp>
// #include <boost/intrusive/rbtree.hpp>
// #include <boost/dynamic_bitset.hpp>
// #include <boost/geometry.hpp>
// #include <boost/geometry/geometries/linestring.hpp>
// #include <boost/geometry/geometries/polygon.hpp>
// #include <boost/geometry/geometries/point_xy.hpp>
// #include <boost/math/tools/minima.hpp>
// using boost::math::tools::brent_find_minima;
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
namespace mp = boost::multiprecision;
typedef mp::number<mp::cpp_dec_float<256>> cdouble;
typedef mp::cpp_int cint;

#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/priority_queue.hpp>
#include<ext/pb_ds/tag_and_trait.hpp>
template<typename T=long long>using pbds=__gnu_pbds::tree<T,__gnu_pbds::null_type,less<T>,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>;
template<typename T=long long>using pbds_map=__gnu_pbds::tree<T,T,less<T>,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>;
template<typename T=long long>using pqueue =__gnu_pbds::priority_queue<T, less<T>,__gnu_pbds::rc_binomial_heap_tag>;
typedef long long lint;
typedef long long ll;
typedef long double ldouble;
typedef vector<lint> vec;
typedef vector<vector<lint>> mat;
typedef vector<vector<vector<lint>>> mat3;
typedef vector<double> dvec;
typedef vector<vector<double>> dmat;
typedef vector<vector<vector<double>>> dmat3;
typedef vector<string> svec;
typedef vector<vector<string>> smat;
typedef vector<vector<vector<string>>> smat3;
typedef vector<pair<lint,lint>> pvec;
typedef vector<vector<pair<lint,lint>>> pmat;
typedef vector<vector<vector<pair<lint,lint>>>> pmat3;
#define rep(i, n) for(lint i = 0; i < (lint)(n); i++)
#define irep(i) for(lint i = 0;; i++)
#define irep1(i) for(lint i = 1;; i++)
#define irep2(i) for(lint i = 2;; i++)
#define rrep(i, n) for(lint i = (lint)(n-1); i >-1; i--)
#define rrepi(i,a,b) for(lint i = (lint)(b-1); i >a-1; i--)
#define repi(i,a,b) for(lint i=lint(a);i<lint(b);i++)
#define rep2(i,a,b,c) for(lint i=lint(a);i>lint(b);i+=c)
#define all(x) (x).begin(),(x).end()
#define PI 3.141592653589793
#define dist(x1,y1,x2,y2) (pow(pow(x2-x1,2)+pow(y2-y1,2),0.5))
#define input(a,n) lint n;cin>>n;vector<lint>a(n);rep(i,n)cin>>a[i];
#define SUM(v) accumulate(all(v),0LL)
#define INF (1LL<<60)
#define IINF (1<<30)
#define EPS (1e-10)
#define LINF 9223372036854775807
//#define MOD 998244353LL
#define MOD 1000000007LL
#define endl "\n"
template<typename T>inline void numout(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i<INF/2?i:"INF";f=1;}cout<<endl;}
template<typename T>inline void numout2(T t){for(auto i:t)numout(i);}
template<typename T>inline void output(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i;f=1;}cout<<endl;}
template<typename T>inline void output2(T t){for(auto i:t)output(i);}
template<typename T>inline void _output(T t){bool f=0;for(int i=0;i<t.size();i++){cout<<f?"":" "<<t[i];f=1;}cout<<endl;}
template<typename T>inline void _output2(T t){for(int i=0;i<t.size();i++)output(t[i]);}
auto Y=[&](auto f){return[&](auto... args){return f(f, args...);};};
template<typename T=lint>T in(){return *istream_iterator<T>(cin);}
template<typename T=lint>inline T gcd(T a,T b){return b?gcd(b,a%b):a;}
template<typename T=lint>inline T lcm(T a,T b){return a/gcd(a,b)*b;}
template<typename T=lint>inline T minq(T a,T b){return min(a,b);}
inline bool chmin(auto& s,const auto& t){bool res=s>t;s=min(s,t);return res;}
inline bool chmax(auto& s,const auto& t){bool res=s<t;s=max(s,t);return res;}
vector<lint> dx={-1,1,0,0,1,1,-1,-1};
vector<lint> dy={0,0,-1,1,1,-1,1,-1};

template<typename T>
class dual_segment{
	struct node;
	using np=node*;
	using lint=long long;
	struct node{
		T t;
		np ch[2];
		node(T t):t(t){}
	};
	np root=nullptr;
	lint n=1,sz;
	T e;
	function<T(T,T)>f;
	public:
	dual_segment(lint sz,T e,function<T(T,T)>f):sz(sz),e(e),f(f){while(n<sz)n<<=1;}
	void set(lint l,lint r,T x){set(l,r,x,-sz,sz,root);}
	T get(lint x){return get(x,-sz,sz,root);}
	private:
	void eval(np t){
		if(!t)t=new node(e);
		if(t->t==e)return;
		if(!t->ch[0])t->ch[0]=new node(e);
		if(!t->ch[1])t->ch[1]=new node(e);
		t->ch[0]->t=f(t->ch[0]->t,t->t);
		t->ch[1]->t=f(t->ch[1]->t,t->t);
		t->t=e;
	}
	void set(lint l,lint r,T x,lint a,lint b,np t){
		eval(t);
		if(r<=a||b<=l)return;
		else if(a<=l&&r<=b){
			t->t=f(t->t,x);
			eval(t);
		}else if(r-l>=2){
			set(l,r,x,a,(a+b)/2,t->ch[0]);
			set(l,r,x,(a+b)/2,b,t->ch[1]);
		}
	}
	T get(T x,lint l,lint r,np t){
		eval(t);
		if(x<l||r<=x)return e;
		else if(l==x&&r==x+1){
			return t->t;
		}else{
			return f(get(x,l,(l+r)/2,t->ch[0]),get(x,(l+r)/2,r,t->ch[1]));
		}
	}
};

lint bs(lint mn,lint mx,function<bool(lint)> func) {
    lint left = mn-1;
    lint right =mx+1;
    while (right - left > 1) {
        lint mid = left + (right - left) / 2;
        if (!func(mid)) right = mid;
        else left = mid;
    }
    return left;
}

int main(){
	lint n,k;
	cin>>n>>k;
	vec a(n),v(n+1,0);
	rep(i,n)cin>>a[i];
	rep(i,n)a[i]--;
	rep(i,n)v[i+1]=v[i]+a[i];
	rep(i,n+1)v[i]%=k;
	map<lint,lint>m;
	lint ans=0;
	rep(i,n+1){
		ans+=m[v[i]];
		m[v[i]]++;
		if(i-k+1>=0)m[v[i-k+1]]--;
	}
	cout<<ans<<endl;
}

Measured memory_bytes: 15872