using System;

using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        new Magatro().Solve();
    }
}

public class Scanner
{
    private StreamReader Sr;

    private string[] S;
    private int Index;
    private const char Separator = ' ';

    public Scanner(Stream source)
    {
        Index = 0;
        S = new string[0];
        Sr = new StreamReader(source);
    }

    private string[] Line()
    {
        return Sr.ReadLine().Split(Separator);
    }

    public string Next()
    {
        string result;
        if (Index >= S.Length)
        {
            S = Line();
            Index = 0;
        }
        result = S[Index];
        Index++;
        return result;
    }
    public int NextInt()
    {
        return int.Parse(Next());
    }
    public double NextDouble()
    {
        return double.Parse(Next());
    }
    public long NextLong()
    {
        return long.Parse(Next());
    }
    public decimal NextDecimal()
    {
        return decimal.Parse(Next());
    }
    public string[] StringArray(int index = 0)
    {
        Next();
        Index = S.Length;
        return S.Skip(index).ToArray();
    }
    public int[] IntArray(int index = 0)
    {
        return StringArray(index).Select(int.Parse).ToArray();
    }
    public long[] LongArray(int index = 0)
    {
        return StringArray(index).Select(long.Parse).ToArray();
    }
    public bool EndOfStream
    {
        get { return Sr.EndOfStream; }
    }
}

public class Magatro
{
    private Scanner Cin;

    private int N, K;
    private int[] S;
    private void Scan()
    {
        Cin = new Scanner(Console.OpenStandardInput());
        N = Cin.NextInt();
        K = Cin.NextInt();
        S = Cin.Next().ToArray().Select(c => int.Parse(c.ToString())).ToArray();
    }
    //なぜこれでいいのか理解してない
    public void Solve()
    {
        Scan();
        int sum = S.Sum();
        if (N <= sum)
        {
            int p = 0;
            int ans = 0;
            for(int i = 0; i < N && i < K; i++)
            {
                 p--;
                while (p < 0)
                {
                    ans++;
                    p++;
                }
                p += S[i];
            }
            Console.WriteLine(ans);
        }
        else
        {
            int ans = K;
            ans -= K / N * sum;
            for (int i = 0; i < K%N; i++)
            {
                ans -= S[i];
            }
            int w = 0;
            int t = 0;
            int c = 0;
            for (int i = K-1; i >=0&&c<100 ; i--)
            {
                t += S[i % N];
                if (t > w)
                {
                    w = t;
                    c = 0;
                }
                t--;
                c++;
            }
            ans += w;
            Console.WriteLine(ans);
        }
    }
}