problem

You decide to invite your friends of the school and your friends of a friend to the Christmas party. The number of students in your school is n, and each student is assigned a number from 1 to n. Your number is 1. You have a list of who and who are your friends. Based on this list, create a program that asks for the number of students you will invite to your Christmas party.



input

The input consists of multiple datasets. Each dataset is given in the following format.

The first line of the dataset contains the number of students in the school n (2 ≤ n ≤ 500), and the second line contains the length of the list m (1 ≤ m ≤ 10000). The input consists of 2 + m lines in total. Line 2 + i (1 ≤ i ≤ m) contains two integers ai and bi (1 ≤ ai <bi ≤ n) separated by blanks, and the students with numbers ai and bi are friends. Represents that. From the 3rd line to the 2 + m line, the lines representing the same friendship do not appear twice.

When both n and m are 0, it indicates the end of input. The number of data sets does not exceed 5.

output

For each dataset, print the number of students you invite to the Christmas party on one line.

Examples

Input

6
5
1 2
1 3
3 4
2 3
4 5
6
5
2 3
3 4
4 5
5 6
2 5
0
0


Output

3
0


Input

None


Output

None
import java.io.InputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;
import java.math.BigInteger;

public class Main{

static PrintWriter out;
static InputReader ir;

static void solve(){
 for(;;){
  int n=ir.nextInt();
  int m=ir.nextInt();
  if(n==0) return;
  G g=new G(n,true);
  for(int i=0;i<m;i++) g.addEdge(ir.nextInt()-1,ir.nextInt()-1,1);
  int[] d=g.dijkstra(0);
  int cnt=0;
  for(int i=1;i<n;i++) if(d[i]<=2) cnt++;
  out.println(cnt);
 }
}

static class G{

 AL[] g;
 private int V;
 private boolean ndir;

 public G(int V,boolean ndir){
  this.V=V;
  this.ndir=ndir;
  g=new AL[V];
  for(int i=0;i<V;i++){
   g[i]=new AL();
  }
 }

 public void addEdge(int u,int v,int t){
  g[u].add(new int[]{v,t});
  if(this.ndir) g[v].add(new int[]{u,t});
 }

 public void addEdge(int u,int v){
  addEdge(u,v,0);
 }

 public int[] dijkstra(int s){
  int[] dist=new int[this.V];
  java.util.PriorityQueue<int[]> pque=new java.util.PriorityQueue<int[]>(11,new Comparator<int[]>(){
   public int compare(int[] a,int[] b){
    return Integer.compare(a[0],b[0]);
   }
  });
  Arrays.fill(dist,1<<26);
  dist[s]=0;
  pque.offer(new int[]{0,s});
  while(!pque.isEmpty()){
   int[] p=pque.poll();
   int v=p[1];
   if(dist[v]<p[0]) continue;
   for(int i=0;i<g[v].size();i++){
    int to=g[v].get(i)[0],cost=g[v].get(i)[1];
    if(dist[to]>dist[v]+cost){
     dist[to]=dist[v]+cost;
     pque.offer(new int[]{dist[to],to});
    }
   }
  }
  return dist;
 }

 public int[] buildTPO(){
  boolean[] vis=new boolean[this.V];
  ArrayList<Integer> ord=new ArrayList<>();
  for(int i=0;i<this.V;i++) if(!vis[i]) ts(i,vis,ord);
  int[] ret=new int[V];
  for(int i=ord.size()-1;i>=0;i--) ret[ord.size()-1-i]=ord.get(i);
  return ret;
 }

 private void ts(int now,boolean[] vis,ArrayList<Integer> ord){
  vis[now]=true;
  int to;
  for(int i=0;i<g[now].size();i++){
   to=g[now].get(i)[0];
   if(!vis[to]) ts(to,vis,ord);
  }
  ord.add(now);
 }

 static class AL extends ArrayList<int[]>{};
}

public static void main(String[] args) throws Exception{
 ir=new InputReader(System.in);
 out=new PrintWriter(System.out);
 solve();
 out.flush();
}

static class InputReader {
 private InputStream in;
 private byte[] buffer=new byte[1024];
 private int curbuf;
 private int lenbuf;

 public InputReader(InputStream in) {this.in=in; this.curbuf=this.lenbuf=0;}
 
 public boolean hasNextByte() {
  if(curbuf>=lenbuf){
   curbuf= 0;
   try{
    lenbuf=in.read(buffer);
   }catch(IOException e) {
    throw new InputMismatchException();
   }
   if(lenbuf<=0) return false;
  }
  return true;
 }

 private int readByte(){if(hasNextByte()) return buffer[curbuf++]; else return -1;}
 
 private boolean isSpaceChar(int c){return !(c>=33&&c<=126);}
 
 private void skip(){while(hasNextByte()&&isSpaceChar(buffer[curbuf])) curbuf++;}
 
 public boolean hasNext(){skip(); return hasNextByte();}
 
 public String next(){
  if(!hasNext()) throw new NoSuchElementException();
  StringBuilder sb=new StringBuilder();
  int b=readByte();
  while(!isSpaceChar(b)){
   sb.appendCodePoint(b);
   b=readByte();
  }
  return sb.toString();
 }
 
 public int nextInt() {
  if(!hasNext()) throw new NoSuchElementException();
  int c=readByte();
  while (isSpaceChar(c)) c=readByte();
  boolean minus=false;
  if (c=='-') {
   minus=true;
   c=readByte();
  }
  int res=0;
  do{
   if(c<'0'||c>'9') throw new InputMismatchException();
   res=res*10+c-'0';
   c=readByte();
  }while(!isSpaceChar(c));
  return (minus)?-res:res;
 }
 
 public long nextLong() {
  if(!hasNext()) throw new NoSuchElementException();
  int c=readByte();
  while (isSpaceChar(c)) c=readByte();
  boolean minus=false;
  if (c=='-') {
   minus=true;
   c=readByte();
  }
  long res = 0;
  do{
   if(c<'0'||c>'9') throw new InputMismatchException();
   res=res*10+c-'0';
   c=readByte();
  }while(!isSpaceChar(c));
  return (minus)?-res:res;
 }

 public double nextDouble(){return Double.parseDouble(next());}

 public BigInteger nextBigInteger(){return new BigInteger(next());}

 public int[] nextIntArray(int n){
  int[] a=new int[n];
  for(int i=0;i<n;i++) a[i]=nextInt();
  return a;
 }

 public long[] nextLongArray(int n){
  long[] a=new long[n];
  for(int i=0;i<n;i++) a[i]=nextLong();
  return a;
 }

 public char[][] nextCharMap(int n,int m){
  char[][] map=new char[n][m];
  for(int i=0;i<n;i++) map[i]=next().toCharArray();
  return map;
 }
}
}