//Nguyen Huu Hoang Minh
#include <bits/stdc++.h>
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define reset(x) memset(x, 0,sizeof(x))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define N 50005
#define remain(x) if (x > MOD) x -= MOD
#define ii pair<int, int>
#define iiii pair< ii , ii >
#define viiii vector< iiii >
#define vi vector<int>
#define vii vector< ii >
#define bit(x, i) (((x) >> (i)) & 1)
#define Task "test"
#define int long long

using namespace std;

typedef long double ld;
const int inf = 1e10;
const int minf = -1e10;

int n, m;
vector<ii> g[N];
int cau[100005];
int num[N], low[N], cnt;
vector<int> g2[N];
vector<int> g3[N];
struct edge{
    int u, v;
} e[100005];
int root;
int st[100005];
int sn;

int tplt;
int dai_dien[10005];
int head[10005];

void dfs(int u, int pre){
    num[u] = low[u] = ++cnt;
    for(auto i : g[u]){
        int v = i.fi;
        int id = i.se;
        if (v==pre) continue;
        if (num[v]) low[u] = min(low[u],num[v]);
        else{
            dfs(v,u);
            low[u] = min(low[u],low[v]);
            if (low[v]>=num[v]){
                cau[id] = 1;
            }
        }
    }
}

void readfile()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    if (fopen(Task".inp","r"))
    {
        freopen(Task".inp","r",stdin);
        //freopen(Task".out","w",stdout);
    }
    cin >> n >> m;
    for(int i=1; i<=m; i++){
        int u, v;
        cin >> u >> v;
        g[u].pb(ii(v,i));
        g[v].pb(ii(u,i));
        e[i] = {u,v};
    }
}

void DFS(int u){
    dai_dien[u] = tplt;
    for(auto v : g2[u]){
        if (!dai_dien[v]){
            DFS(v);
        }
    }
}

vector<int> leaf;

void DFS_arrange(int u, int pre){
    for(auto v : g3[u]){
        if (v!=pre){
            DFS_arrange(v,u);
        }
    }
    if (g3[u].size()==1 && u!=1) leaf.pb(u);
}

void proc()
{
    for(int i=1; i<=n; i++){
        if (num[i]==0){
            dfs(i,i);
        }
    }
    for(int i=1; i<=m; i++){
        if (!cau[i]){
            int u = e[i].u;
            int v = e[i].v;
            g2[u].pb(v);
            g2[v].pb(u);
        }
    }
    for(int i=1; i<=n; i++){
        if (!dai_dien[i]){
            ++tplt;
            head[tplt] = i;
            DFS(i);
        }
    }
    for(int i=1; i<=n; i++){
        int u = dai_dien[i];
        for(auto j : g[i]){
            int v = j.fi;
            v = dai_dien[v];
            if (u!=v){
                g3[u].pb(v);
                g3[v].pb(u);
            }
        }
    }
    for(int i=1; i<=tplt; i++){
        if (g3[i].size()){
            sort(all(g3[i]));
            g3[i].erase(unique(all(g3[i])),g3[i].end());
        }
    }


    // phần này là nối nè gs :v phần trên đệ nén đồ thị
    vector<ii> res;
    DFS_arrange(1,1);
    for(auto x : leaf){
        if (sn < 3){
            st[++sn] = x;
        }
        if (sn==3){
            int u = head[st[1]];
            int v = head[st[3]];
            res.pb(ii(u,v));
            st[1] = st[2];
            sn = 1;
        }
    }
    if (sn==2){
        res.pb(ii(head[st[1]],head[st[2]]));
    }
    if (sn==1 || g3[1].size()==1){
        res.pb(ii(head[st[1]],1));
    }

    cout << res.size() << '\n';
    for(auto tmp : res) cout << tmp.fi << ' ' << tmp.se << '\n';
}

signed main()
{
    readfile();
    proc();
    return 0;
}