#include <cstdio>
#include <algorithm>
#include <ctype.h>
#include <iostream>
#include <cstring>
#include <vector>
#include <queue>

using namespace std;

inline int read() {
    int x = 0, f = 1;
    char ch = getchar();

    while (!isdigit(ch)) {
        if (ch == '-')
            f = -1;

        ch = getchar();
    }

    while (isdigit(ch)) {
        x = x * 10 + ch - '0';
        ch = getchar();
    }

    return x * f;
}

const int N = 1000005;

int head[N], to[N * 2], nxt[N * 2], pre[N], deg[N], DEG[N], cnt = 1;

void add(int u, int v) {
    to[++cnt] = v;
    nxt[cnt] = head[u];
    head[u] = cnt;
    pre[cnt] = u;
}

int n, m;

void work1() {
    queue<int>Q;
    bool vis[N] = {0};

    for (int i = 1; i <= n; i++)
        if (deg[i] == 1)
            Q.push(i), vis[i] = 1;

    while (!Q.empty()) {
        int now = Q.front();
        Q.pop();

        for (int i = head[now]; i; i = nxt[i]) {
            int v = to[i];

            if (!vis[v] && (--deg[v]) == 1)
                Q.push(v), vis[v] = 1;
        }
    }
}

bool vis[N];

void work2() {
    queue<int>Q;

    for (int i = 1; i <= n; i++)
        if (deg[i] >= 2)
            Q.push(i), vis[i] = 1;

    while (!Q.empty()) {
        int now = Q.front();
        Q.pop();

        for (int i = head[now]; i; i = nxt[i]) {
            int v = to[i];

            if (!vis[v] && deg[v] == 1)
                Q.push(v), vis[v] = 1;
        }
    }
}

vector<pair<int, int>>ans;

int main() {
    n = read(), m = read();

    for (int i = 1; i <= m; i++) {
        int u = read(), v = read();
        add(u, v);
        add(v, u);
        DEG[u]++, DEG[v]++;
        deg[u]++, deg[v]++;
    }

    work1();
    work2();

    //  for(int i=1;i<=n;i++)
    //      printf("%d %d %d\n",deg[i],DEG[i],vis[i]);
    for (int i = 1; i <= cnt; i += 2) {
        int x = pre[i], y = to[i];

        if (vis[x] || vis[y]) {
            //          printf("!!!%d %d\n",x,y);
            if ((deg[x] == 1 && deg[y] == 1) || (deg[x] > 1 && deg[y] > 1))
                continue;

            if (deg[x] == 1)
                ans.push_back(make_pair(y, x));
            else
                ans.push_back(make_pair(x, y));
        } else if (!vis[x] && !vis[y]) {
            if (DEG[y] == 1)
                ans.push_back(make_pair(y, x));

            if (DEG[x] == 1)
                ans.push_back(make_pair(x, y));
        }
    }

    sort(ans.begin(), ans.end());
    printf("%d\n", ans.size());

    for (int i = 0; i < (int)ans.size(); i++)
        printf("%d %d\n", ans[i].first, ans[i].second);

    return 0;
}