Each day in Berland consists of n hours. Polycarp likes time management. That's why he has a fixed schedule for each day — it is a sequence a_1, a_2, ..., a_n (each a_i is either 0 or 1), where a_i=0 if Polycarp works during the i-th hour of the day and a_i=1 if Polycarp rests during the i-th hour of the day.

Days go one after another endlessly and Polycarp uses the same schedule for each day.

What is the maximal number of continuous hours during which Polycarp rests? It is guaranteed that there is at least one working hour in a day.

Input

The first line contains n (1 ≤ n ≤ 2⋅10^5) — number of hours per day.

The second line contains n integer numbers a_1, a_2, ..., a_n (0 ≤ a_i ≤ 1), where a_i=0 if the i-th hour in a day is working and a_i=1 if the i-th hour is resting. It is guaranteed that a_i=0 for at least one i.

Output

Print the maximal number of continuous hours during which Polycarp rests. Remember that you should consider that days go one after another endlessly and Polycarp uses the same schedule for each day.

Examples

Input


5
1 0 1 0 1


Output


2


Input


6
0 1 0 1 1 0


Output


2


Input


7
1 0 1 1 1 0 1


Output


3


Input


3
0 0 0


Output


0

Note

In the first example, the maximal rest starts in last hour and goes to the first hour of the next day.

In the second example, Polycarp has maximal rest from the 4-th to the 5-th hour.

In the third example, Polycarp has maximal rest from the 3-rd to the 5-th hour.

In the fourth example, Polycarp has no rest at all.
//package sept;

import java.io.*;
import java.util.*;


public class TimePass implements Runnable {
    InputStream is;
    PrintWriter out;
    String INPUT = "";
    //boolean debug=false;
    boolean debug=true;
    static long mod=998244353;
    static long mod2=1000000007;
    
    void solve() throws IOException
	{
	    int n=ni();
	    int[] a=na(n);
	    int[] c=new int[2*n];
	    for(int i=0;i<n;i++)
	    {
	        c[i]=a[i];
	        c[n+i]=a[i];
	    }
	    int cnt=c[0];
	    for(int i=1;i<2*n;i++)
	    {
	        if(c[i]==1)
	        {
	            c[i]=c[i-1]+1;
	        }
	        cnt=Math.max(cnt,c[i]);
	    }
	    out.println(cnt);
	}
	
	static int comp(int n)
	{
	    if(n<10)return n;
	    int sum=0;
	    while(n>0)
	    {
	        sum+=n%10;
	        n/=10;
	    }
	    return comp(sum);
	}
	
	static long fnc(int a,int b)
	{
	    return a+(long)1000000007*b;
	}
	
	static Pair[][] packU(int n,int[] from,Pair[] to)
	{
		Pair[][] g=new Pair[n][];
		int[] p=new int[n];
		for(int f:from)
		{
			p[f]++;
		}
		int m=from.length;
		for(int i=0;i<n;i++)
		{
			g[i]=new Pair[p[i]];
		}
		for(int i=0;i<m;i++)
		{
			g[from[i]][--p[from[i]]]=to[i];
		}
		return g;
	}

	static int[][] packD(int n,int[] from,int[] to)
	{
		int[][] g=new int[n][];
		int[] p=new int[n];
		for(int f:from)
		{
			p[f]++;
		}
		int m=from.length;
		for(int i=0;i<n;i++)
		{
			g[i]=new int[p[i]];
		}
		for(int i=0;i<m;i++)
		{
			g[from[i]][--p[from[i]]]=to[i];
		}
		return g;
	}
	    
    static class Pair
    {
        int a,b,c;
        public Pair(int a,int b
        //,int c
        )
        {
            this.a=a;
            this.b=b;
            //this.c=c;
        }
    }
    
    static long lcm(int a,int b)
    {
        long val=a;
        val*=b;
        return (val/gcd(a,b));
    }
    
    static long gcd(long a,long b)
    {
        if(a==0)return b;
        return gcd(b%a,a);
    }
    
    static int pow(int a, int b, int p)
    {
        long ans = 1, base = a;
        while (b!=0)
        {
            if ((b & 1)!=0)
            {
                ans *= base;
                ans%= p;
            }
            base *= base;
            base%= p;
            b >>= 1;
        }
        return (int)ans;
    }

    static int inv(int x, int p)
    {
        return pow(x, p - 2, p);
    }
    
    public static long[] radixSort(long[] f){ return radixSort(f, f.length); }
	public static long[] radixSort(long[] f, int n)
	{
		long[] to = new long[n];
		{
			int[] b = new int[65537];
			for(int i = 0;i < n;i++)b[1+(int)(f[i]&0xffff)]++;
			for(int i = 1;i <= 65536;i++)b[i]+=b[i-1];
			for(int i = 0;i < n;i++)to[b[(int)(f[i]&0xffff)]++] = f[i];
			long[] d = f; f = to;to = d;
		}
		{
			int[] b = new int[65537];
			for(int i = 0;i < n;i++)b[1+(int)(f[i]>>>16&0xffff)]++;
			for(int i = 1;i <= 65536;i++)b[i]+=b[i-1];
			for(int i = 0;i < n;i++)to[b[(int)(f[i]>>>16&0xffff)]++] = f[i];
			long[] d = f; f = to;to = d;
		}
		{
			int[] b = new int[65537];
			for(int i = 0;i < n;i++)b[1+(int)(f[i]>>>32&0xffff)]++;
			for(int i = 1;i <= 65536;i++)b[i]+=b[i-1];
			for(int i = 0;i < n;i++)to[b[(int)(f[i]>>>32&0xffff)]++] = f[i];
			long[] d = f; f = to;to = d;
		}
		{
			int[] b = new int[65537];
			for(int i = 0;i < n;i++)b[1+(int)(f[i]>>>48&0xffff)]++;
			for(int i = 1;i <= 65536;i++)b[i]+=b[i-1];
			for(int i = 0;i < n;i++)to[b[(int)(f[i]>>>48&0xffff)]++] = f[i];
			long[] d = f; f = to;to = d;
		}
		return f;
	}

    
    public void run()
    {
        if(debug)oj=true;
        is = oj ? System.in : new ByteArrayInputStream(INPUT.getBytes());
        out = new PrintWriter(System.out);
        
        long s = System.currentTimeMillis();
        try {
			solve();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
        out.flush();
        tr(System.currentTimeMillis()-s+"ms");
    }
    
    public static void main(String[] args) throws Exception {new Thread(null,new TimePass(),"Main",1<<26).start();}
    
    private byte[] inbuf = new byte[1024];
    public int lenbuf = 0, ptrbuf = 0;
    
    private int readByte()
    {
        if(lenbuf == -1)throw new InputMismatchException();
        if(ptrbuf >= lenbuf){
            ptrbuf = 0;
            try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
            if(lenbuf <= 0)return -1;
        }
        return inbuf[ptrbuf++];
    }
    
    private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
    private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
    
    private double nd() { return Double.parseDouble(ns()); }
    private char nc() { return (char)skip(); }
    
    private String ns()
    {
        int b = skip();
        StringBuilder sb = new StringBuilder();
        while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    
    private char[] ns(int n)
    {
        char[] buf = new char[n];
        int b = skip(), p = 0;
        while(p < n && !(isSpaceChar(b))){
            buf[p++] = (char)b;
            b = readByte();
        }
        return n == p ? buf : Arrays.copyOf(buf, p);
    }
    
    private char[][] nm(int n, int m)
    {
        char[][] map = new char[n][];
        for(int i = 0;i < n;i++)map[i] = ns(m);
        return map;
    }
    
    private int[] na(int n)
    {
        int[] a = new int[n];
        for(int i = 0;i < n;i++)a[i] = ni();
        return a;
    }
    
    private int ni()
    {
        int num = 0, b;
        boolean minus = false;
        while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        
        while(true){
            if(b >= '0' && b <= '9'){
                num = num * 10 + (b - '0');
            }else{
                return minus ? -num : num;
            }
            b = readByte();
        }
    }
    
    private long nl()
    {
        long num = 0;
        int b;
        boolean minus = false;
        while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        
        while(true){
            if(b >= '0' && b <= '9'){
                num = num * 10 + (b - '0');
            }else{
                return minus ? -num : num;
            }
            b = readByte();
        }
    }
    
    private boolean oj = System.getProperty("ONLINE_JUDGE") != null;
    private void tr(Object... o) { if(!oj)System.out.println(Arrays.deepToString(o)); }
}