Problem: Bob got a job as a system administrator in X corporation. His first task was to connect n servers with the help of m two-way direct connection so that it becomes possible to transmit data from one server to any other server via these connections. Each direct connection has to link two different servers, each pair of servers should have at most one direct connection. Y corporation, a business rival of X corporation, made Bob an offer that he couldn't refuse: Bob was asked to connect the servers in such a way, that when server with index v fails, the transmission of data between some other two servers becomes impossible, i.e. the system stops being connected. Help Bob connect the servers.

Input

The first input line contains 3 space-separated integer numbers n, m, v (3 ≤ n ≤ 105, 0 ≤ m ≤ 105, 1 ≤ v ≤ n), n — amount of servers, m — amount of direct connections, v — index of the server that fails and leads to the failure of the whole system.

Output

If it is impossible to connect the servers in the required way, output -1. Otherwise output m lines with 2 numbers each — description of all the direct connections in the system. Each direct connection is described by two numbers — indexes of two servers, linked by this direct connection. The servers are numbered from 1. If the answer is not unique, output any.

Examples

Input

5 6 3


Output

1 2
2 3
3 4
4 5
1 3
3 5


Input

6 100 1


Output

-1

Solution (in JAVA):

Solution:

	
	    /*
	     * Author- Priyam Vora
	     * BTech 2nd Year DAIICT
	     */
	     
	            
	    import java.io.*;
	    import java.math.*;
	    import java.util.*;
	    import javax.print.attribute.SetOfIntegerSyntax;
	     
	    public class CodeMonk_Graph {
	    	private static InputStream stream;
	    	private static byte[] buf = new byte[1024];
	    	private static int curChar;
	    	private static int numChars;
	    	private static SpaceCharFilter filter;
	    	private static PrintWriter pw;
	    	private static long count = 0,mod=1000000007;
	    	private static TreeSet<Integer>ts[]=new TreeSet[200000];
	    	private static HashSet hs=new HashSet();
	     
	    	public static void main(String args[]) throws Exception {
	    		InputReader(System.in);
	    		pw = new PrintWriter(System.out);
	    		//ans();
	    		soln();
	    		pw.close();
	    	}
	     
	    	public static long gcd(long x, long y) {
	    		if (x == 0)
	    			return y;
	    		else
	    			return gcd( y % x,x);
	    	}
	    	
	    	private static int BinarySearch(int a[], int low, int high, int target) {
	    		if (low > high)
	    			return -1;
	    		int mid = low + (high - low) / 2;
	    		if (a[mid] == target)
	    			return mid;
	    		if (a[mid] > target)
	    			high = mid - 1;
	    		if (a[mid] < target)
	    			low = mid + 1;
	    		return BinarySearch(a, low, high, target);
	    	}
	    	
	    	public static String reverseString(String s) {
	    		StringBuilder sb = new StringBuilder(s);
	    		sb.reverse();
	    		return (sb.toString());
	    	}
	    	
	    	public static long pow(long n, long p) {
	    		if(p==0)
	    			return 1;
	    		if(p==1)
	    			return n%mod;
	    		if(p%2==0){
	    			long temp=pow(n, p/2);
	    		return (temp*temp)%mod;
	    		}else{
	    			 	long temp=pow(n,p/2);
	    			 	temp=(temp*temp)%mod;
	    			 	return(temp*n)%mod;
	    			 	
	    		}
	    	}
	     
	    		
	     
	    	public static int[] radixSort(int[] f) {
	    		int[] to = new int[f.length];
	    		{
	    			int[] b = new int[65537];
	    			for (int i = 0; i < f.length; i++)
	    				b[1 + (f[i] & 0xffff)]++;
	    			for (int i = 1; i <= 65536; i++)
	    				b[i] += b[i - 1];
	    			for (int i = 0; i < f.length; i++)
	    				to[b[f[i] & 0xffff]++] = f[i];
	    			int[] d = f;
	    			f = to;
	    			to = d;
	    		}
	    		{
	    			int[] b = new int[65537];
	    			for (int i = 0; i < f.length; i++)
	    				b[1 + (f[i] >>> 16)]++;
	    			for (int i = 1; i <= 65536; i++)
	    				b[i] += b[i - 1];
	    			for (int i = 0; i < f.length; i++)
	    				to[b[f[i] >>> 16]++] = f[i];
	    			int[] d = f;
	    			f = to;
	    			to = d;
	    		}
	    		return f;
	    	}
	     
	    	public static int nextPowerOf2(final int a) {
	    		int b = 1;
	    		while (b < a) {
	    			b = b << 1;
	    		}
	    		return b;
	    	}
	     
	    	public static boolean PointInTriangle(int p1, int p2, int p3, int p4, int p5, int p6, int p7, int p8) {
	    		int s = p2 * p5 - p1 * p6 + (p6 - p2) * p7 + (p1 - p5) * p8;
	    		int t = p1 * p4 - p2 * p3 + (p2 - p4) * p7 + (p3 - p1) * p8;
	     
	    		if ((s < 0) != (t < 0))
	    			return false;
	     
	    		int A = -p4 * p5 + p2 * (p5 - p3) + p1 * (p4 - p6) + p3 * p6;
	    		if (A < 0.0) {
	    			s = -s;
	    			t = -t;
	    			A = -A;
	    		}
	    		return s > 0 && t > 0 && (s + t) <= A;
	    	}
	     
	    	public static float area(int x1, int y1, int x2, int y2, int x3, int y3) {
	    		return (float) Math.abs((x1 * (y2 - y3) + x2 * (y3 - y1) + x3 * (y1 - y2)) / 2.0);
	    	}
	     
	    	public static boolean isPrime(int n) {
	    		// Corner cases
	    		if (n <= 1)
	    			return false;
	    		if (n <= 3)
	    			return true;
	     
	    		// This is checked so that we can skip 
	    		// middle five numbers in below loop
	    		if (n % 2 == 0 || n % 3 == 0)
	    			return false;
	     
	    		for (int i = 5; i * i <= n; i = i + 6)
	    			if (n % i == 0 || n % (i + 2) == 0)
	    				return false;
	     
	    		return true;
	    	}
	     
	    	//merge Sort
	     
	    	static long sort(int a[])
	    	{  int n=a.length;
	    		int b[]=new int[n];	
	    		return mergeSort(a,b,0,n-1);}
	    	static long mergeSort(int a[],int b[],long left,long right)
	    	{ long c=0;if(left<right)
	    	 {   long mid=left+(right-left)/2;
	    		 c= mergeSort(a,b,left,mid);
	    		 c+=mergeSort(a,b,mid+1,right);
	    		 c+=merge(a,b,left,mid+1,right); }	
	    		return c;	 }
	    	static long merge(int a[],int  b[],long left,long mid,long right)
	    	{long c=0;int i=(int)left;int j=(int)mid; int k=(int)left;
	    	while(i<=(int)mid-1&&j<=(int)right)
	    	{ if(a[i]>a[j]) {b[k++]=a[i++]; }
	    	else	{ b[k++]=a[j++];c+=mid-i;}}
	    	while (i <= (int)mid - 1)   b[k++] = a[i++]; 
	    	while (j <= (int)right) b[k++] = a[j++];
	    	for (i=(int)left; i <= (int)right; i++) 
	    		a[i] = b[i];  return c;  }
	    	public static boolean isSubSequence(String large, String small, int largeLen, int smallLen) {
	    		//base cases
	    		if (largeLen == 0)
	    			return false;
	    		if (smallLen == 0)
	    			return true;
	    		// If last characters of two strings are matching
	    		if (large.charAt(largeLen - 1) == small.charAt(smallLen - 1))
	    			isSubSequence(large, small, largeLen - 1, smallLen - 1);
	    		// If last characters are not matching
	    		return isSubSequence(large, small, largeLen - 1, smallLen);
	    	}
	     
	    	// To Get Input
	    	// Some Buffer Methods
	     
	    	public static void InputReader(InputStream stream1) {
	    		stream = stream1;
	    	}
	     
	    	private static boolean isWhitespace(int c) {
	    		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	    	}
	     
	    	private static boolean isEndOfLine(int c) {
	    		return c == '\n' || c == '\r' || c == -1;
	    	}
	     
	    	private static int read() {
	    		if (numChars == -1)
	    			throw new InputMismatchException();
	    		if (curChar >= numChars) {
	    			curChar = 0;
	    			try {
	    				numChars = stream.read(buf);
	    			} catch (IOException e) {
	    				throw new InputMismatchException();
	    			}
	    			if (numChars <= 0)
	    				return -1;
	    		}
	    		return buf[curChar++];
	    	}
	     
	    	private static int nextInt() {
	    		int c = read();
	    		while (isSpaceChar(c))
	    			c = read();
	    		int sgn = 1;
	    		if (c == '-') {
	    			sgn = -1;
	    			c = read();
	    		}
	    		int res = 0;
	    		do {
	    			if (c < '0' || c > '9')
	    				throw new InputMismatchException();
	    			res *= 10;
	    			res += c - '0';
	    			c = read();
	    		} while (!isSpaceChar(c));
	    		return res * sgn;
	    	}
	     
	    	private static long nextLong() {
	    		int c = read();
	    		while (isSpaceChar(c))
	    			c = read();
	    		int sgn = 1;
	    		if (c == '-') {
	    			sgn = -1;
	    			c = read();
	    		}
	    		long res = 0;
	    		do {
	    			if (c < '0' || c > '9')
	    				throw new InputMismatchException();
	    			res *= 10;
	    			res += c - '0';
	    			c = read();
	    		} while (!isSpaceChar(c));
	    		return res * sgn;
	    	}
	     
	    	private static String nextToken() {
	    		int c = read();
	    		while (isSpaceChar(c))
	    			c = read();
	    		StringBuilder res = new StringBuilder();
	    		do {
	    			res.appendCodePoint(c);
	    			c = read();
	    		} while (!isSpaceChar(c));
	    		return res.toString();
	    	}
	     
	    	private static String nextLine() {
	    		int c = read();
	    		while (isSpaceChar(c))
	    			c = read();
	    		StringBuilder res = new StringBuilder();
	    		do {
	    			res.appendCodePoint(c);
	    			c = read();
	    		} while (!isEndOfLine(c));
	    		return res.toString();
	    	}
	     
	    	private static int[] nextIntArray(int n) {
	    		int[] arr = new int[n];
	    		for (int i = 0; i < n; i++) {
	    			arr[i] = nextInt();
	    		}
	    		return arr;
	    	}
	     
	    	private static int[][] next2dArray(int n, int m) {
	    		int[][] arr = new int[n][m];
	    		for (int i = 0; i < n; i++) {
	    			for (int j = 0; j < m; j++) {
	    				arr[i][j] = nextInt();
	    			}
	    		}
	    		return arr;
	    	}
	    	private static char[][] nextCharArray(int n,int m){
	    		char [][]c=new char[n][m];
	    		for(int i=0;i<n;i++){
	    			String s=nextLine();
	    			for(int j=0;j<s.length();j++){
	    				c[i][j]=s.charAt(j);
	    			}
	    		}
	    		return c;
	    	}
	     
	    	private static long[] nextLongArray(int n) {
	    		long[] arr = new long[n];
	    		for (int i = 0; i < n; i++) {
	    			arr[i] = nextLong();
	    		}
	    		return arr;
	    	}
	     
	    	private static void pArray(int[] arr) {
	    		for (int i = 0; i < arr.length; i++) {
	    			pw.print(arr[i] + " ");
	    		}
	    		pw.println();
	    		return;
	    	}
	     
	    	private static void pArray(long[] arr) {
	    		for (int i = 0; i < arr.length; i++) {
	    			pw.print(arr[i] + " ");
	    		}
	    		pw.println();
	    		return;
	    	}
	     
	    	private static void pArray(boolean[] arr) {
	    		for (int i = 0; i < arr.length; i++) {
	    			pw.print(arr[i] + " ");
	    		}
	    		pw.println();
	    		return;
	    	}
	     
	    	private static boolean isSpaceChar(int c) {
	    		if (filter != null)
	    			return filter.isSpaceChar(c);
	    		return isWhitespace(c);
	    	}
	     
	    	private interface SpaceCharFilter {
	    		public boolean isSpaceChar(int ch);
	    	}
	     
	    	//----------------------------------------My Code------------------------------------------------//
	

	    	private static void soln() {
	    	
	    		HashSet hs=new HashSet();
	    		long n=nextLong();
	    		long m=nextLong();
	    		int v=nextInt();
	    		
	    		long tot_ed=(((n-1)*(n-2))/2)+1;
	    		if(m>=(n-1) && m<=tot_ed)
	    		{
	    			int arr[]=new int[(int)n+1];

	    			for(int i=1;i<=n;i++){
	    				arr[i]=i;
	    				
	    			}
	    			int tot_edge=1;
	    			arr[2]=v;
	    			arr[v]=2;
	    			pw.println(arr[1]+" "+arr[2]);
	    			for(int i=3;i<=n;i++){
	    				if(tot_edge==m)
	    					break;
	    				pw.println(arr[2]+" "+arr[i]);
	    			tot_edge++;
	    			}
	    			for(int i=3;i<=n;i++){
	    				for(int j=i+1;j<=n;j++){
	    					if(tot_edge==m){
	    						i=(int)n;
	    						break;
	    					}
	    					pw.println(arr[i]+" "+arr[j]);
	    				tot_edge++;
	    				}
	    			}
	    			
	    			if(tot_edge!=m){
	    				System.out.println(-1);
	    				System.exit(0);
	    			}
	    		}else{
	    			pw.println(-1);
	    		}
	    	}
	    	
	    		
	    		//-----------------------------------------The End--------------------------------------------------------------------------//
	    
	    
	    
	 }
	    	
	   
	    
		class Pair implements Comparable<Pair>{
		    long id; 
			long w;
			long h;
			Pair(long id,long w,long h){
				this.id=id;
				this.w=w;
				this.h=h;
			}
			@Override
			public int compareTo(Pair o) {
				// TODO Auto-generated method stub
			//	Sort in increasing order
				if(id<o.id)
					return 1;
				else if(id>o.id)
					return -1;
					else{
						if(w<o.w)
							return 1;
						else if(w>o.w)
							return -1;
						else{
							if(h<o.h){
								return 1;
							}else if(o.h>h)
								return -1;
							else return 0;
						}
					}

				
				
			}
		
		}
	        class Graph{
	        	private static int V,level[][],count=-1,lev_dfs[],degree=0,no_vert_conn_comp=0;
	        	private Stack <Integer>st=new Stack();
	        	private static LinkedList<Integer > adj[];
	        	private boolean[][] Visite;
	        	private static boolean [] Visited;
	        	private static TreeSet<Integer> ts=new TreeSet();
	    Graph(int V){
	    V++;
	    this.V=(V);
	    adj=new LinkedList[V];
	    Visite=new boolean[100][100];

 	   Visited=new boolean[V];
	    level=new int[100][100];
	   lev_dfs=new int[V]; 
	   for(int i=0;i<V;i++)
		   adj[i]=new LinkedList<Integer>();
	    }
	     
	    void addEdge(int v,int w){
	    	
	    	if(adj[v]==null){
	    		adj[v]=new LinkedList();
	    	}
	    	adj[v].add(w);
	     
	    	
	    }
	 
	    public static int BFS2(int startVert,int dest){
	    	Visited=new boolean[V];
	    	for(int i=1;i<V;i++){
	    		lev_dfs[i]=-1;
	    	}
	    	Queue<Integer> q=new LinkedList<Integer>();
	    	q.add(startVert);
	    	
	    	lev_dfs[startVert]=0;
	    	while(!q.isEmpty()){
	    		int top=q.poll();
	    		
	    		Iterator<Integer> i= adj[top].listIterator();
	    		while(i.hasNext()){
	    			int n=i.next();
	    			if(!Visited[n]){
	    				q.add(n);
	    				Visited[n]=true;
	    				lev_dfs[n]=lev_dfs[top]+1;
	    			if(n==dest){
	    				q.clear();
	    				return lev_dfs[n];
	    			
	    			}
	    			}
	    		}
	    	}
	    	q.clear();
	    	return -1;
	    }
	    public int getEd(){
	    	return degree/2;
	    }
	    public void get(int from,int to){
	    	int h=lev_dfs[from]-lev_dfs[to];
	    	if(h<=0){
	    		System.out.println(-1);
	    	}else{
	    		System.out.println(h-1);
	    	}
	    }
	    private static boolean check(int x,int y,char c[][]){
		
			if((x>=0 && y>=0) && (x<c.length && y<c[0].length) && c[x][y]!='#'){
				
				return true;
			}
			return false;
		}
	    public int BFS(int x,int y,int k,char[][] c)
	    {
	    	 LinkedList<Pair> queue = new LinkedList<Pair>();
	        //Visited[s]=true;
	   //     queue.add(new Pair(x,y));
	       int count=0;
	   level[x][y]=-1;
	   c[x][y]='M';
	        while (!queue.isEmpty())
	        {
	            Pair temp = queue.poll();
	            //x=temp.idx;
	            //y=temp.val;
	            
	            c[x][y]='M';
	      // System.out.println(x+" "+y+" ---"+count);
	         count++;
	     	if(count==k)
	         {
	         	for(int i=0;i<c.length;i++){
	         		for(int j=0;j<c[0].length;j++){
	         			if(c[i][j]=='M'){
	         				System.out.print(".");
	         			}
	         			else if(c[i][j]=='.')
	         				System.out.print("X");
	         			else
	         				System.out.print(c[i][j]);
	         		}
	         		System.out.println();
	         	}
	         System.exit(0);
	         }
	     	
	         // System.out.println(x+" "+y);
	           // V--;
	           
	        }
	        return V;
	    }
	    
	    private void getAns(int startVertex){
	    	for(int i=0;i<adj[startVertex].size();i++){
	    		int ch=adj[startVertex].get(i);
	    		for(int j=0;j<adj[ch].size();j++){
	    			int ch2=adj[ch].get(j);
	    			if(adj[ch2].contains(startVertex)){
	    				System.out.println(startVertex+" "+ch+" "+ch2);
	    				System.exit(0);
	    			}
	    		}
	    	}
	    }
	    
	     public long dfs(int startVertex){
	    //	 getAns(startVertex);
	    	 
	    	 if(!Visited[startVertex])  {
	    
	   return dfsUtil(startVertex,Visited);
	    	//return getAns();
	    	}
	    	 
	    
	     
	    return 0;
	    	}
	 private long dfsUtil(int startVertex, boolean[] Visited) {//0-Blue 1-Pink
	 
		 int c=1;
		 long cout=0;
	      degree=0;
	    	Visited[startVertex]=true;
	    	lev_dfs[startVertex]=1;
	      st.push(startVertex);
	    while(!st.isEmpty()){
	    	
	    	int top=st.pop();
	    int child=adj[top].size();
	    if(top!=startVertex)
	    	child--;
	    
	    	ts.add(top);
	    	Iterator<Integer> i=adj[top].listIterator();
	     degree+=adj[top].size();
	     
	    while(i.hasNext()){
	    //	System.out.println(top);
	    	int n=i.next();
	     if( !Visited[n]){
	    				Visited[n]=true;
	    					st.push(n);
	    					if(adj[n].size()-1>child)
	    					cout++;	
	    				c++;
	    					lev_dfs[n]=lev_dfs[top]+1;
	    			
	    		 }
	         }
	 }
	    return cout;
	    	
	    		
	    
	  //  System.out.println("NO");
	   // return c;
	    	
	    
	    
	    
	    }
	        
	        }     
	        	
	        
	    class Dsu{
	    	private int rank[], parent[] ,n;
	    	
	    	Dsu(int size){
	    		this.n=size+1;
	    		rank=new int[n];
	    		parent=new int[n];
	    	makeSet();
	    	}
	    	
	    	void makeSet(){
	    		for(int i=0;i<n;i++){
	    			parent[i]=i;
	    		}
	    	}
	    	
	    	int find(int x){
	    		if(parent[x]!=x){
	    			
	    			parent[x]=find(parent[x]);
	    		}
	    		return parent[x];
	    	}	
	    	
	    	void union(int x,int y){
	    		int xRoot=find(x);
	    		int yRoot=find(y);
	    		
	    		if(xRoot==yRoot)
	    			return;
	    		if(rank[xRoot]<rank[yRoot]){
	    		parent[xRoot]=yRoot;	
	    		}else if(rank[yRoot]<rank[xRoot]){
	    			parent[yRoot]=xRoot;
	    		}else{
	    			parent[yRoot]=xRoot;
	    			rank[xRoot]++;
	    		}
	    		
	    	}
	     
	    }
	    class Heap{
	    	
	    	public static void build_max_heap(long []a,int size){
	    		
	    		for(int i=size/2;i>0;i--){
	    			max_heapify(a, i,size);
	    		}
	    		
	    			}
	    	private static void max_heapify(long[] a,int i,int size){
	    		int left_child=2*i;
	    		int right_child=(2*i+1);
	    		int largest=0;
	    		
	    		if(left_child<size && a[left_child]>a[i]){
	    			largest=left_child;
	    		}else{
	    			largest=i;
	    		}
	    		
	    		if(right_child<size && a[right_child]>a[largest]){
	    			largest=right_child;
	    		}
	    		if(largest!=i){
	    			long temp=a[largest];
	    			a[largest]=a[i];
	    			a[i]=temp;
	    			max_heapify(a, largest,size);
	    		}
	    	}
	    	private static void min_heapify(int[] a,int i){
	    		int left_child=2*i;
	    		int right_child=(2*i+1);
	    		int largest=0;
	    		
	    		if(left_child<a.length && a[left_child]<a[i]){
	    			largest=left_child;
	    		}else{
	    			largest=i;
	    		}
	    		
	    		if(right_child<a.length && a[right_child]<a[largest]){
	    			largest=right_child;
	    		}
	    		if(largest!=i){
	    			int temp=a[largest];
	    			a[largest]=a[i];
	    			a[i]=temp;
	    			min_heapify(a, largest);
	    		}
	    	}
	    	public static void extract_max(int size,long a[]){
	    		if(a.length>1){
	    			long max=a[1];
	    			a[1]=a[a.length-1];
	    			size--;
	    			max_heapify(a, 1,a.length-1);
	    		}
	    	}
	    }
	    
	    class MyComp implements Comparator<Long>{
	        
			@Override
			public int compare(Long o1, Long o2) {
				if(o1<o2){
					return 1;
				}else if(o1>o2){
					return -1;
				}
				return 0;
				
			}
	    }