#include <cstdio>
#include <stack>
#include <vector>
#define nmax 100005

using namespace std;
int N,m,sol;
vector<int>G[nmax],b[nmax];
stack<int>ST;
int niv[nmax],low[nmax];
bool viz[nmax];

inline void DF(int nod,int tata,int lev){

  niv[nod] = low[nod] = lev;
  for(auto it: G[nod])
    if(it != tata){
        if(viz[it])
            low[nod] = min(low[nod],niv[it]);
            else{
                    ST.push(it);
                    viz[it] = true;

                DF(it,nod,lev+1);

                low[nod] = min(low[nod],low[it]);

                if(niv[nod] <= low[it]){
                        ++sol;
                        b[sol].push_back(nod);
                  while(!ST.empty()){
                    b[sol].push_back(ST.top());
                    if(ST.top()==it){
                    ST.pop();
                    break;
                    }
                    ST.pop();
                  }
                }
            }

    }

}
int main(){
    int i,x,y;
    freopen("biconex.in","r",stdin);
    freopen("biconex.out","w",stdout);
    scanf("%d %d\n",&N,&m);
    for(i = 1; i <= m; ++i){
        scanf("%d %d",&x,&y);
        G[x].push_back(y);
        G[y].push_back(x);
    }
    viz[1] = true;
    ST.push(1);
   DF(1,0,1);
   printf("%d\n",sol);
    for(i = 1; i <= sol; ++i){
        for(auto it: b[i])
            printf("%d ",it);
        printf("\n");
    }
    return 0;
}