using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Runtime.CompilerServices;
using ll=System.Int64;

public class Contest
{
	static void Swap1<T>(ref T a, ref T b) { T t = a; a = b; b = t; }
	static void Swap2<T>(ref T a, ref T b) where T : IComparable { if (a.CompareTo(b)==1) Swap1(ref a, ref b); }  // b の方が小さければ交換
	static bool Chmin<T>(ref T a, T b) where T : IComparable { if (a.CompareTo(b)== 1) { a = b; return true; } return false; }  // b の方が小さければ a を更新
	static bool Chmax<T>(ref T a, T b) where T : IComparable { if (a.CompareTo(b)==-1) { a = b; return true; } return false; }  // b の方が大きければ a を更新
	static T[][] InitMat<T>(long len1, long len2, T val){ T[][] m = new T[len1][]; for (int i = 0; i < m.Length; i++) m[i] = Enumerable.Repeat(val, (int)len2).ToArray(); return m; }
	static T[][][] InitMat<T>(long len1, long len2, long len3, T val){ T[][][] m = new T[len1][][]; for (int i = 0; i < m.Length; i++) m[i] = InitMat(len2,len3,val); return m; }
	public const long MOD1 = 1000000007; // 10^9+7
	public const double EPS1 = 1e-8;

	public static void Main() {
		Solve_E();
 	}

	public static void Solve_A() {
		string s;
		MyIO.ReadMulti(out s);


		long ans = 0;

		if(s=="SUN") ans = 7;
		if(s=="MON") ans = 6;
		if(s=="TUE") ans = 5;
		if(s=="WED") ans = 4;
		if(s=="THU") ans = 3;
		if(s=="FRI") ans = 2;
		if(s=="SAT") ans = 1;



		MyIO.WriteMulti(ans);
	}
	public static void Solve_B() {
		long  n;
		MyIO.ReadMulti(out n);
		string s;
		MyIO.ReadMulti(out s);

		StringBuilder ans = new StringBuilder();
		foreach (var e in s)
		{
			ans.Append((char)(((byte)e+(byte)n-65)%26+65));
		}

		MyIO.WriteMulti(ans.ToString());
	}
	public static void Solve_C() {
		long  a,b,x;
		MyIO.ReadMulti(out a, out b, out x);

		Func<ll,ll,bool> f = (i,l)=>{
			return (a*i+b*i.ToString().Length)<=l;
		};

        long left = 0; //「index = 0」が条件を満たすこともあるので、初期値は -1
        long right = 1000000001; // 「index = a.size()-1」が条件を満たさないこともあるので、初期値は a.size()

        // どんな二分探索でもここの書き方を変えずにできる！
        while (right - left > 1) {
            long mid = left + (right - left) / 2;

            if (!f(mid,x)) right = mid;
            else left = mid;
        }




		MyIO.WriteMulti(left);
	}
	public static void Solve_D() {
		long  n;
		MyIO.ReadMulti(out n);
		VT<ll,ll>[] abl;
		MyIO.ReadLines(n-1,out abl);

		ll[] color = new ll[n-1];
		ll cmax = 0;
		ll root = -1;

		List<VT<ll,ll>>[] tree = new List<VT<ll, ll>>[n];
		for (int i = 0; i < n-1; i++)
		{
			if(tree[abl[i].Item1-1]==null)tree[abl[i].Item1-1]=new List<VT<ll, ll>>();
			if(tree[abl[i].Item2-1]==null)tree[abl[i].Item2-1]=new List<VT<ll, ll>>();
			tree[abl[i].Item1-1].Add(new VT<ll, ll>(abl[i].Item2-1,i));
			tree[abl[i].Item2-1].Add(new VT<ll, ll>(abl[i].Item1-1,i));
		}

		for (int i = 0; i < n; i++)
		{
			if(cmax<tree[i].Count){
				cmax = tree[i].Count;
				root = i;
			}
		}

		Func<ll,ll,ll,bool> dfs = null;
		dfs = (e,pi,pc)=>{
			if(e==pi) return false;
			ll cc = 1;
			foreach (var i in tree[e])
			{
				if(i.Item1==pi) continue;
				if(cc==pc) cc++;
				color[i.Item2] = cc;
				dfs(i.Item1,e,cc);

				cc++;
			}

			return true;
		};

		dfs(root,-1,-1);

		MyIO.WriteMulti(cmax);
		MyIO.WriteLines(color);


	}
	public static void Solve_E() {
		long  n, k;
		MyIO.ReadMulti(out n, out k);
		ll[] a;
		MyIO.ReadArray(out a);

		ll[] b = new ll[n+1];
		b[0] = 0;
		for (int i = 0; i < n; i++)
		{
			b[i+1] = (b[i] + a[i] - 1) % k ;
		}

		ll ans = 0;
		if(n<k) {
			Dictionary<ll,ll> d = new Dictionary<ll, ll>();
			for (int i = 0; i < n+1; i++)
			{
				if(!d.ContainsKey(b[i])) d[b[i]]=0;
				d[b[i]]++;
			}
			foreach (var kv in d)
			{
				ans += kv.Value*(kv.Value-1)/2;
			}
		}else{
			ll[] segcnt = new ll[k];
			for (int i = 0; i < n+1; i++)
			{
				if(k<=i) segcnt[b[i-k]]--;
				ans += segcnt[b[i]];
				segcnt[b[i]]++;
			}
		}


		MyIO.WriteMulti(ans);
	}
	public static void Solve_F() {
		long  n, m;
		MyIO.ReadMulti(out n, out m);



		long ans = 0;

		MyIO.WriteMulti(ans);
	}


















}




















#region MyIO

public struct VT<T, U>
{
	public T Item1; public U Item2;
    public VT(T a, U b) { Item1 = a; Item2 = b; }
}
public struct VT<T, U, V>
{
	public T Item1; public U Item2; public V Item3;
    public VT(T a, U b, V c) { Item1 = a; Item2 = b; Item3 = c; }
}
public struct VT<T, U, V, W>
{
	public T Item1; public U Item2; public V Item3; public W Item4;
    public VT(T a, U b, V c, W d) { Item1 = a; Item2 = b; Item3 = c; Item4 = d; }
}

public class Printer : System.IO.StreamWriter
{
	public override IFormatProvider FormatProvider { get { return System.Globalization.CultureInfo.InvariantCulture; } }
	public Printer(System.IO.Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
	public Printer(System.IO.Stream stream, Encoding encoding) : base(stream, encoding) { }
}
public static class MyIO
{
	private static char[] splitter = new char[] {' '};
	private static bool eq<T, U>() => typeof(T).Equals(typeof(U));
	private static T ct<T, U>(U a) => (T)Convert.ChangeType(a, typeof(T));
	private static T cv<T>(string s) =>
		eq<T, int>()    ? ct<T, int>(int.Parse(s))
	  : eq<T, long>()   ? ct<T, long>(long.Parse(s))
	  : eq<T, double>() ? ct<T, double>(double.Parse(s, System.Globalization.CultureInfo.InvariantCulture))
	  : eq<T, char>()   ? ct<T, char>(s[0])
						: ct<T, string>(s);
			
	public static string[] ReadMulti<T>(out T a) {
		var ar = Console.ReadLine().Split(splitter, StringSplitOptions.RemoveEmptyEntries); 
		a = cv<T>(ar[0]);
		return ar;
	}
	public static string[] ReadMulti<T, U>(out T a, out U b) {
		var ar = ReadMulti<T>(out a); 
        b = cv<U>(ar[1]);
		return ar;
	}
	public static string[] ReadMulti<T, U, V>(out T a, out U b, out V c) {
		var ar = ReadMulti<T, U>(out a, out b); 
        c = cv<V>(ar[2]);
		return ar;
	}
	public static string[] ReadMulti<T, U, V, W>(out T a, out U b, out V c, out W d) {
		var ar = ReadMulti<T, U, V>(out a, out b, out c); 
        d = cv<W>(ar[3]);
		return ar;
	}
	public static string[] ReadMulti<T, U, V, W, X>(out T a, out U b, out V c, out W d, out X e) {
		var ar = ReadMulti<T, U, V, W>(out a, out b, out c, out d); 
        e = cv<X>(ar[4]);
		return ar;
	}
	public static string[] ReadMulti<T, U, V, W, X, Y>(out T a, out U b, out V c, out W d, out X e, out Y f) {
		var ar = ReadMulti<T, U, V, W, X>(out a, out b, out c, out d, out e); 
        f = cv<Y>(ar[5]);
		return ar;
	}
	public static string[] ReadArray<T>(out T[] a) {		
		var ar = Console.ReadLine().Split(splitter, StringSplitOptions.RemoveEmptyEntries);
		a = ar.Select(cv<T>).ToArray();
		return ar;
	}		
	public static string[][] ReadLines<T>(long n, out T[] a) {
		a = new T[n];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) arr[i] = ReadMulti(out a[i]);
		return arr;
	}
	public static string[][] ReadLines<T, U>(long n, out VT<T, U>[] a) {
		a = new VT<T, U>[n];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) {
			T o; U p;
			arr[i] = ReadMulti(out o, out p);
			a[i] = new VT<T, U>(o, p);
		}
		return arr;
	}
	public static string[][] ReadLines<T, U, V>(long n, out VT<T, U, V>[] a) {
		a = new VT<T, U, V>[n];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) {
			T o; U p; V q;
			arr[i] = ReadMulti(out o, out p, out q);
			a[i] = new VT<T, U, V>(o, p, q);
		}
		return arr;
	}
	public static string[][] ReadLines<T, U, V, W>(long n, out VT<T, U, V, W>[] a) {
		a = new VT<T, U, V, W>[n];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) {
			T o; U p; V q; W r;
			arr[i] = ReadMulti(out o, out p, out q, out r);
			a[i] = new VT<T, U, V, W>(o, p, q, r);
		}
		return arr;
	}
	public static string[][] ReadMatrix<T>(long n, out T[][] a) {
		a = new T[n][];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) arr[i] = ReadArray(out a[i]);
		return arr;
	}

	private static void wwp(Action act){
		var sw = new Printer(Console.OpenStandardOutput()){AutoFlush = false};
		Console.SetOut(sw);
		act();
		Console.Out.Flush();
		sw.AutoFlush = true;
		Console.SetOut(sw);
	}
	private static string wfm(Type t) =>t.Equals(typeof(double)) ? "{0:F10}" : "{0}";
	public static void WriteMulti(params object[] a) {
		wwp(()=>{
			for(int i=0;i<a.Length;i++) {
				string fs = wfm(a[i].GetType()) + ((i<a.Length-1) ? " " : Environment.NewLine);
				Console.Write(fs, a[i]);
			}
		});
	}
	public static void WriteArray<T>(T[] a) {
		wwp(()=>{
			string fs = wfm(typeof(T));
			string fs1 = fs + " ";
			string fs2 = fs + Environment.NewLine;
			for(int i=0;i<a.Length;i++) Console.Write( ((i<a.Length-1) ? fs1 : fs2), a[i]);
		});
	}
	public static void WriteLines<T>(T[] a) {
		wwp(()=>{
			string fs = wfm(typeof(T)) + Environment.NewLine;
			foreach(T x in a) Console.Write(fs, x);
		});
	}


}

#endregion



Measured memory_bytes: 46660