#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,abm,mmx,avx,avx2,popcnt,tune=native")
//#pragma GCC optimize("fast-math")
#pragma GCC optimize("unroll-loops")
#pragma comment(linker, "/STACK:36777216")

#define _CRT_SECURE_NO_WARNINGS
#include <chrono>
#include <set>
#include <map>
#include <deque>
#include <cmath>
#include <queue>
#include <cassert>
#include <random>
#include <bitset>
#include <iomanip>
#include <numeric>
#include <time.h>//////////////
#include <ctime>
#include <string>
#include <cstdio>
#include <vector>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <unordered_set>
//++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++
#define endl '\n'
#define mp make_pair
#define pbc push_back
#define pob pop_back()
#define empb emplace_back
#define queuel queue<long long>
#define sqr(a) ((a) * (a))
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define pin(p) cin >> p.first >> p.second;
#define uniq(a) sort(all(a));(a).resize(unique(all(a)) - a.begin());
#define rev(v) reverse(v.begin(), v.end());
#define sout(s, c) for (auto i : s) cout << i << c;
#define pout(p) cout << p.first << " " << p.second;
#define er(v, l, r) erase(v.begin() + l, v.begin() + r);
#define vin(v) for (ll i = 0; i < v.size(); ++i) cin >> v[i];
#define vout(v, c) for (int i = 0; i < v.size(); ++i) cout << v[i] << c;
#define pushi(v, a) for (int i = 0; i < a.size(); ++i) v.push_back(a[i]);
#define fastio() ios_base::sync_with_stdio(0); cout.tie(0); cin.tie(0); srand(time(NULL))
#define sp system("pause")
//++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++
using namespace std;
//++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
//++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++
const ld EPS = 1e-4;
const int inf = 1e9;
const ld PI = acos(-1);
int mod = (int)998244353;
const int MOD7 = 1000000007;
const int MOD9 = 1000000009;
const int a228 = 18;
const ll kekmod = 1791791791;
const ll bestmod = 1148822869;
const ll secmod = (int) 1e9 + 113;
vector<ll> mods = { kekmod,bestmod,mod,MOD9,1000000007 };
vector<ll> hashpows = { 29,31,37,43,47,53,179,229 };
const int MAXN = 1e5 + 229;
mt19937 rnd(chrono::high_resolution_clock::now().time_since_epoch().count() + 228 + 'i' + 'q' + 1337 + 1488);
ll MOD = mods[rnd() % mods.size()];
ll hashpow = hashpows[rand() % hashpows.size()];

signed main()
{
	fastio();
	int n, k;
	cin >> n >> k;
	vector<int> a(n);
	vin(a);
	vector<int> pref(n);
	pref[0] = a[0] % k;

	for (int i = 1; i < n; ++i)
	{
		a[i] %= k;
		pref[i] = pref[i - 1] + a[i];
		pref[i] %= k;
	}
	map<int, int> lol;
//	lol[0] ++;
	
	ll ans = 0;
	for (int i = 0; i < n; ++i)
	{
		if (i - k >= 0) lol[(pref[i - k] - (i - k) - 1 + 1ll * n * k) % k] --;
		ans += lol[(pref[i] - i - 1 + 1ll * n * k ) % k];
		if (i < k  - 1)
		{
			if ((pref[i] - i - 1) % k == 0) ans++;
		}
		lol[(pref[i] - i - 1 + 1ll * n * k) % k] ++;
	}
	/*for (int i = 0; i < n; ++i)
	{
		if ( i >=k && a[i] % k == 1) ans++;
	}*/
	cout << ans;
	sp;
}


Measured memory_bytes: 11392