#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <array>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <sstream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <list>
#include <numeric>
#include <stack>
#include <iomanip>
#include <random>
#include <complex>
#include <functional>
#include <tuple>

using namespace std;

#define Rep(i,a,b) for(int i = a; i < b; ++i)
#define rep(i,b) Rep(i,0,b)
#define allof(a) (a).begin(), (a).end()

#define Yes(q) ((q) ? "Yes" : "No")
#define YES(q) ((q) ? "YES" : "NO")
#define Possible(q) ((q) ? "Possible" : "Impossible")
#define POSSIBLE(q) ((q) ? "POSSIBLE" : "IMPOSSIBLE")

using ll = long long;

using pint = std::pair<int, int>;
using pll = std::pair<ll, ll>;


constexpr int inf = 1e9 + 7;
constexpr ll infll = 1ll << 60ll;
constexpr ll mod = 1e9 + 7;
// 0~3までは右左下上 4~7までは斜め
constexpr int dx[] = { 1, 0, -1, 0, 1, 1, -1, -1 };
constexpr int dy[] = { 0, -1, 0, 1, 1, -1, -1, 1 };

namespace {
	template<typename T> void chmax(T& a, T b) { a = std::max(a, b); }
	template<typename T> void chmin(T& a, T b) { a = std::min(a, b); }
	template<typename T> void chadd(T& a, T b) { a = a + b; }

	void Cout(long long x, const char* end = "\n") { std::cout << x << end; }
	template <typename T> void Cout(const T& x, const char* end = "\n") { std::cout << x << end; }
	template <typename T> void Cout(const std::vector<T>& x, const char* sep = " ", const char* end = "\n") { for (std::size_t i = 0, sz = x.size(); i < sz; i++) { std::cout << x[i] << (i == sz - 1 ? end : sep); } }

	void CCout(long long x, const char* end = "\n") { std::cerr << x << end; }
	template <typename T> void CCout(const T& x, const char* end = "\n") { std::cerr << x << end; }
	template <typename T> void CCout(const std::vector<T>& x, const char* sep = " ", const char* end = "\n") { for (std::size_t i = 0, sz = x.size(); i < sz; i++) { std::cerr << x[i] << (i == sz - 1 ? end : sep); } }

	// 標準入出力
	struct inp {
		std::size_t sz;
		inp(std::size_t _sz = 1) : sz(_sz) {}
		template <typename T> operator T () const { T a; std::cin >> a; return a; }
		template <typename T> operator std::vector<T>() const { vector<T> a(sz); for (std::size_t i = 0; i < sz; i++) std::cin >> a[i]; return a; }
		template <typename T, typename U> operator std::pair<T, U>() const { T f; U s; std::cin >> f >> s; return std::pair<T, U>(f, s); }
	};

	inp inp1; // input one
}

int main() {

	ll n, k;
	cin >> n >> k;
	vector<ll> a = inp(n);

	// 1 4 2 3 5

	// 要素の数はまぁまぁ制御できるからなんとかなりそう

	vector<ll> sum(n, 0);
	sum[0] = a[0];
	rep(i, n - 1) {
		sum[i + 1] = sum[i] + a[i + 1];
	}
	
	// 要素数がk以上の時が対応できない
	ll ans = 0;
	map<ll, ll> mp;
	int right = 0;
	for (int left = 0; left < n; ++left) {

		if (right == n) break;

		// rightを伸ばす
		while (right < left + k) {
			// 当てはまる数だけ増やす
			if (right < k && (sum[right] % k == right + 1)) {
				//cout << "default right : " << right  << endl;
				++ans;
			}
			ll value = (sum[right] - right - 1) % k;
			//cout << "right : " << right << ", value : "<< mp.count(value) << endl;
			if(mp.count(value) != 0)
				ans += mp[value];
			mp[value]++;

			++right;
			if (right == n) break;
		}

		ll value = (sum[left] - left - 1) % k;
		if (mp.count(value) != 0) mp[value]--;
	}

	Cout(ans);

	return 0;
}


Measured memory_bytes: 15872