#include <iostream>
#include <vector>
#include <string>
#include <stack>
#include <set>
#include <map>

#include "optimization.h"
#include <unordered_map>

#include <cassert>
#include <cstdio>
#include <algorithm>


using namespace std;
int n, e;
vector<multiset<int>> graph;
//map<pair<int,int>, int> matrix;
map<pair<int, int>, int> bad_matrix;
vector<pair<pair<int, int>, int>> answer;
set<pair<int,int>> bad;
void dfs(int v) {
    while (!graph[v].empty()) {
        int x = *graph[v].begin();
        graph[v].erase(graph[v].find(x));
        graph[x].erase(graph[x].find(v));
        dfs(x);
        if (bad.find({x,v}) != bad.end()) {
            bad.erase(bad.find({x,v}));
            bad.erase(bad.find({v,x}));
            answer.push_back({{v, x}, 1});
        }else{
            answer.push_back({{v, x}, 0});

        }

    }

}


int main() {
//    cin >> n >> e;
    n = readInt();
    e = readInt();
    graph.resize(n + 1);
//    matrix.resize(n + 1, vector<int8_t>(n + 1, 0));
//    bad_matrix.resize(n + 1, vector<int8_t>(n + 1, 0));
    vector<int> deg(n + 1, 0);
    for (int i = 0; i < e; i++) {
        int a, b;
//        cin >> a >> b;
        a = readInt();
        b = readInt();
        deg[a] += 1;
        deg[b] += 1;
//        matrix[{b,a}] += 1;
//        matrix[{a,b}] += 1;
        graph[a].insert(b);
        graph[b].insert(a);
    }
    vector<int> n_deg;

    for (int i = 1; i <= n; i++) {
        if (deg[i] % 2 == 1) {
            n_deg.push_back(i);
            if (n_deg.size() == 2) {
                int x = n_deg[0];
                int y = n_deg[1];

                    bad.insert({x,y});
                bad.insert({y,x});
                    graph[x].insert(y);
                    graph[y].insert(x);

                n_deg.clear();
                n_deg.resize(0);
            }
        }
    }

    dfs(1);
    vector<vector<int>> result;
    vector<int> way;

    reverse(answer.begin(), answer.end());
    for (auto [x,y] : answer) {
        auto[w, e] = x;
//        cout << w << ' ' << e << '\n';
        if (y == 0) {
            if (way.empty()) {
                way.push_back(w);
                way.push_back(e);
            } else if (way.back() == w) {
                way.push_back(e);
            } else {
                way.push_back(w);
                way.push_back(e);
            }
        } else {
            if (!way.empty()) {
                result.push_back(way);
            }
            way.clear();
        }
    }

    if (!way.empty()) {
        result.push_back(way);
    }
//    int a = prev(result.end())->size();
    int size = result.size();
    int answer_size = size;
    int a = result.size();
    auto last = (prev(result.end()))->size();
//    if (result.begin() != prev(result.end()) && result[0][0] == result[a - 1][last - 1]) {
//        swap(*result.begin(), *prev(result.end()));
//        writeInt(result.size() - 1, '\n');
//        for (int i = 0; i < result.size(); i++) {
//            if (!result[i].empty() && i != result.size() - 1) {
//                for (int j = 0; j < result[i].size(); j++) {
////                cout << z << ' ';
//                    writeInt(result[i][j], ' ');
//                }
//                if (i == 0) {
//                    for (int j = 1; j < result[result.size() - 1].size(); j++) {
//                        writeInt(result[result.size() - 1][j], ' ');
//                    }
//                }
////            cout << '\n';
//                writeChar('\n');
//            }
//        }
//        return 0;
//    }



            if (size > 1 && result[0][0] == result[size-1][result[size-1].size()-1]){
                answer_size--;
                auto &x = result[0];
                auto &y = result[size-1];
                for (int s = 1; s < x.size(); s++){
                    y.push_back(x[s]);
                }
                x.clear();
            }





//    cout << result.size() << '\n';
    writeInt(answer_size, '\n');
    for (auto x: result) {
        if (!x.empty()) {
            for (auto z: x) {
//                cout << z << ' ';
                writeInt(z, ' ');
            }
//            cout << '\n';
            writeChar('\n');
        }
    }
}


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