#include <stdio.h>
#include <stdlib.h>

int p,c;
int sou[10000], ve[10000], was[10000];
short *e,*f,*g;

void dfs(int v)
{
  int i,w;
  was[v] = 1;
  for (i=0; i<sou[v]; i++) {
    w=e[ve[v]+i];
    if (!was[w]) dfs(w);
  }
}

int main(void)
{
  int a,b,i,j,komp,maxkomp;
  while (scanf(" %d %d", &p, &c), !(p==0 && c==0)) {
    e = (short*)malloc(2*sizeof(short)*c);
    f = (short*)malloc(sizeof(short)*c);
    g = (short*)malloc(sizeof(short)*c);
    
    for (i=0; i<p; i++) sou[i]=ve[i]=was[i]=0;
    
    for (i=0; i<c; i++) {
      scanf(" %d %d", &a, &b);
      sou[a]++; sou[b]++;
      f[i]=a; g[i]=b;
    }
    for (was[0]=ve[0]=0, i=1; i<p; i++) {
      ve[i]=ve[i-1]+sou[i-1];
      was[i]=was[i-1]+sou[i-1];
    }
        
    for (i=0; i<c; i++) {
      e[was[f[i]]] = g[i]; was[f[i]]++;
      e[was[g[i]]] = f[i]; was[g[i]]++;
    }
    free(f); free(g);
    
    maxkomp=0;
    for (i=0; i<p; i++) {
      for (j=0; j<p; j++) was[j] = !!(i==j);
      for (komp=0, j=0; j<p; j++) {
        if (was[j]==0) dfs(j), komp++;
	if (maxkomp<komp) maxkomp=komp;
      }
    }
    printf("%d\n", maxkomp);

    free(e);    
  }
  
  return 0;
}