56
 1
 46
 63478
 7578
 56056
 78
 66873
 8149
 35708
 81207
 41385
 37317
 74424
 67817
 684
 15
 96992
 38798
 19715
 627
 39509
 45899
 31893
 1515
 33
 95298
 27443
 60879
 99
 34378
 57113
 36655
 63359
 873
 67341
 100000
 42863
 35
 250
 573
 23
 871
 15748
 92763
 9564
 42602
 38
 42237
 70878
 93764
 303

-1
 -1
 4
 -1
 3
 -1
 4
 2
 2
 -1
 6
 15
 -1
 21
 73
 -1
 2
 -1
 76
 -1
 2
 -1
 -1
 3
 2
 2
 4
 2
 2
 2
 -1
 2
 -1
 34
 18
 2
 -1
 -1
 -1
 5
 3
 -1
 -1
 8
 22
 3
 17
 -1
 18
 -1
 -1
 2

import java.io.*;
import java.util.*;
/*
 * Heart beats fast
 * 		Colors and promises
 * 			How to be brave
 * 				How can I love when I am afraid...
 */
//read the question correctly (is y a vowel? what are the exact constraints?)
//look out for SPECIAL CASES (n=1?) and overflow (ll vs int?)
//always declare multidimensional arrays as [2][n] not [n][2]
//it can lead to upto 2-3x diff in runtime
//declare int/long tries with 16 array size due to object overhead :D
public class Main
{
	
	public static void main(String[] args) throws Exception
	{
		int[]grundy=new int[100001];
		@SuppressWarnings("unchecked")
		Set<Integer>[]hola=new HashSet[100001];
		for(int i=0; i<=100000; i++)
			hola[i]=new HashSet<Integer>();
		int n=ni();
		int ans=100000000;
		for(int i=2; i<=100000; i++)
		{
			int g=0;
			//grundy's number is mex of set of grundy numbers of children
			while(hola[i].contains(g))
				g++;
			grundy[i]=g;
			int xorian=grundy[i],sum=i;
			for(int j=i-1; j>=1; j--)
			{
				sum+=j;
				xorian^=grundy[j];
				if(sum>100000)
					break;
				hola[sum].add(xorian);
				if(sum==n&&xorian==0)
					ans=min(ans,i-j+1);
			}
		}
		if(grundy[n]!=0)
			sop(ans);
		else
			sop(-1);
		System.out.print(output);
	}
	///////////////////////////////////////////
	///////////////////////////////////////////
	///template from here
	static class pair
	{
		int a, b;
		pair(){}
		pair(int c,int d){a=c;b=d;}
	}
	static interface combiner
	{
		public int combine(int a, int b);
	}
	static final int mod=1000000007;
	static final double eps=1e-9;
	static final long inf=100000000000000000L;
	static Reader in=new Reader();
	static StringBuilder output=new StringBuilder();
	static Random rn=new Random();
	static void reverse(int[]a){for(int i=0; i<a.length/2; i++){a[i]^=a[a.length-i-1];a[a.length-i-1]^=a[i];a[i]^=a[a.length-i-1];}}
	static void sort(int[]a)
	{
		int te;
		for(int i=0; i<a.length; i+=2)
		{
			te=rn.nextInt(a.length);
			if(i!=te)
			{
				a[i]^=a[te];
				a[te]^=a[i];
				a[i]^=a[te];
			}
		}
		Arrays.sort(a);
	}
	static void sort(long[]a)
	{
		int te;
		for(int i=0; i<a.length; i+=2)
		{
			te=rn.nextInt(a.length);
			if(i!=te)
			{
			a[i]^=a[te];
			a[te]^=a[i];
			a[i]^=a[te];
			}
		}
		Arrays.sort(a);
	}
	static void sort(double[]a)
	{
		int te;
		double te1;
		for(int i=0; i<a.length; i+=2)
		{
			te=rn.nextInt(a.length);
			if(i!=te)
			{
			te1=a[te];
			a[te]=a[i];
			a[i]=te1;
			}
		}
		Arrays.sort(a);
	}
	static void sort(int[][]a)
	{
		Arrays.sort(a, new Comparator<int[]>()
		{
			public int compare(int[]a,int[]b)
			{
				if(a[0]>b[0])
					return -1;
				if(b[0]>a[0])
					return 1;
				return 0;
			}
		});
	}
	static void sort(pair[]a)
	{
		Arrays.sort(a,new Comparator<pair>()
				{
			@Override
			public int compare(pair a,pair b)
			{
				if(a.a>b.a)
					return 1;
				if(b.a>a.a)
				return -1;
				return 0;
			}
				});
	}
	static int log2n(long a)
	{
		int te=0;
		while(a>0)
		{
			a>>=1;
			++te;
		}
		return te;
	}
	static class vectorl implements Iterable<Long>
	{
		long a[];
		int size;
		vectorl(){a=new long[10];size=0;}
		vectorl(int n){a=new long[n];size=0;}
		public void add(long b){if(++size==a.length)a=Arrays.copyOf(a, 2*size);a[size-1]=b;}
		public void sort(){Arrays.sort(a, 0, size);}
		public void sort(int l, int r){Arrays.sort(a, l, r);}
		@Override
		public Iterator<Long> iterator() {
			Iterator<Long> hola=new Iterator<Long>()
					{
				int cur=0;
						@Override
						public boolean hasNext() {
							return cur<size;
						}
						@Override
						public Long next() {
							return a[cur++];
						}				
					};
			return hola;
		}
	}
	static class vector implements Iterable<Integer>
	{
		int a[],size;
		vector(){a=new int[10];size=0;}
		vector(int n){a=new int[n];size=0;}
		public void add(int b){if(++size==a.length)a=Arrays.copyOf(a, 2*size);a[size-1]=b;}
		public void sort(){Arrays.sort(a, 0, size);}
		public void sort(int l, int r){Arrays.sort(a, l, r);}
		@Override
		public Iterator<Integer> iterator() {
			Iterator<Integer> hola=new Iterator<Integer>()
					{
				int cur=0;
						@Override
						public boolean hasNext() {
							return cur<size;
						}
						@Override
						public Integer next() {
							return a[cur++];
						}				
					};
			return hola;
		}
	}
	//output functions////////////////
	static void pr(Object a){output.append(a+"\n");}
	static void pr(){output.append("\n");}
	static void p(Object a){output.append(a);}
	static void pra(int[]a){for(int i:a)output.append(i+" ");output.append("\n");}
	static void pra(long[]a){for(long i:a)output.append(i+" ");output.append("\n");}
	static void pra(String[]a){for(String i:a)output.append(i+" ");output.append("\n");}
	static void pra(double[]a){for(double i:a)output.append(i+" ");output.append("\n");}
	static void sop(Object a){System.out.println(a);}
	static void flush(){System.out.println(output);output=new StringBuilder();}
	//////////////////////////////////
	//input functions/////////////////
	static int ni(){return Integer.parseInt(in.next());}
	static long nl(){return Long.parseLong(in.next());}
	static String ns(){return in.next();}
	static double nd(){return Double.parseDouble(in.next());}
	static int[] nia(int n){int a[]=new int[n];for(int i=0; i<n; i++)a[i]=ni();return a;}
	static int[] pnia(int n){int a[]=new int[n+1];for(int i=1; i<=n; i++)a[i]=ni();return a;}
	static long[] nla(int n){long a[]=new long[n];for(int i=0; i<n; i++)a[i]=nl();return a;}
	static String[] nsa(int n){String a[]=new String[n];for(int i=0; i<n; i++)a[i]=ns();return a;}
	static double[] nda(int n){double a[]=new double[n];for(int i=0; i<n; i++)a[i]=nd();return a;}
	//////////////////////////////////
	//some utility functions
	static void exit(){System.out.print(output);System.exit(0);}
	static int min(int... a){int min=a[0];for(int i:a)min=Math.min(min, i);return min;}
	static int max(int... a){int max=a[0];for(int i:a)max=Math.max(max, i);return max;}	
	static int gcd(int... a){int gcd=a[0];for(int i:a)gcd=gcd(gcd, i);return gcd;}	
	static long min(long... a){long min=a[0];for(long i:a)min=Math.min(min, i);return min;}
	static long max(long... a){long max=a[0];for(long i:a)max=Math.max(max, i);return max;}	
	static long gcd(long... a){long gcd=a[0];for(long i:a)gcd=gcd(gcd, i);return gcd;}	
	static String pr(String a, long b){String c="";while(b>0){if(b%2==1)c=c.concat(a);a=a.concat(a);b>>=1;}return c;}
	static long powm(long a, long b, long m){long an=1;long c=a;while(b>0){if(b%2==1)an=(an*c)%m;c=(c*c)%m;b>>=1;}return an;}
	static int gcd(int a, int b){if(b==0)return a;return gcd(b, a%b);}
	static long gcd(long a, long b){if(b==0)return a;return gcd(b, a%b);}
	static class Reader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;
        public Reader() {
            reader = new BufferedReader(new InputStreamReader(System.in), 32768);
            tokenizer = null;
        }
        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }
    }
}