int top(si &s1, si& s2){
if(!s2.empty())
return s2.top();
if(s1.empty())
return -1;
while(!s1.empty()){
s2.push(s1.top());
s1.pop();
}
return s2.top();
}
bool solve()
{
int mg,mm;
while(!g.empty() && !m.empty())
{
mg=*g.begin();
mm=*m.begin();
if(mg<mm)
g.erase(g.begin());
else
m.erase(m.begin());
}
return m.empty();
}
void pop(si &s1, si &s2){
if(!s2.empty()){
s2.pop();
return;
}
if(s1.empty())
return;
while(true){
int i=s1.top();
s1.pop();
if(s1.empty())
return;
s2.push(i);
}
}
int main()
{
int n,m,x,y,i;
while(scanf("%d%d", &n, &m)!=EOF)
{
vs.clear();
for(i=0; i<n; ++i) v[i].clear();
for(i=0; i<m; ++i)
{
scanf("%d%d", &x, &y);
--x; --y;
v[x].push_back(y);
v[y].push_back(x);
}
for(i=0; i<n; ++i)
{
s1.insert(i);
sort(v[i].begin(), v[i].end());
}
while(!s1.empty())
{
x=*s1.begin();
s1.erase(x);
s2.clear();
q.push(x);
while(!q.empty())
{
x=q.front(); q.pop();
s2.insert(x);
for(sit=s1.begin(); sit != s1.end();)
{
y=*sit;
++sit;
if(!binary_search(v[x].begin(), v[x].end(), y))
{
q.push(y); s1.erase(y);
}
}
}
vs.push_back(s2);
}
printf("%u\n", vs.size());
for(i=0; i<vs.size(); ++i)
{
printf("%u", vs[i].size());
for(sit=vs[i].begin(); sit != vs[i].end(); ++sit)
{
printf(" %d", *sit+1);
}
puts("");
}
}
return 0;
}