#include <bits/stdc++.h>
using namespace std;

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define RFOR(i, b, a) for (int i = (b) - 1; i >= (a); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

const int MAX = 500'447;
set<int> g[MAX];
bool used[MAX];
bool del[MAX];
VI vert;

void dfs(int v)
{
	used[v] = 1;
	vert.PB(v);
	for (auto to : g[v])
		if (!used[to])
			dfs(to);
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout << fixed << setprecision(15);
	
	int n, m;
	cin >> n >> m;
	FOR (i, 0, m)
	{
		int a, b;
		cin >> a >> b;
		a--, b--;
		g[a].insert(b);
		g[b].insert(a);
	}
	vector<PII> ans;
	FOR (i, 0, n)
	{
		if (!used[i])
		{
			dfs(i);
			int cnt = 0;
			for (auto v : vert)
				cnt += SZ(g[v]);
			assert(cnt % 2 == 0);
			cnt /= 2;
			if (cnt < SZ(vert))
			{
				for (auto v : vert)
				{
					if (SZ(g[v]) == 1)
						ans.PB({v, *g[v].begin()});
				}
			}
			else
			{
				vector<PII> a;
				set<PII> s;
				for (auto v : vert)
				{
					s.insert({SZ(g[v]), v});
				}
				while (s.begin()->F == 1)
				{
					int v = s.begin()->S;
					s.erase(s.begin());
					int u = *g[v].begin();
					
					a.PB({v, u});
					del[v] = 1;
					
					g[v].erase(u);
					
					s.erase({SZ(g[u]), u});
					g[u].erase(v);
					s.insert({SZ(g[u]), u});
				}
				for (auto [v, u] : a)
				{
					assert(del[v]);
					if (!del[u])
						ans.PB({u, v});
				}
			}
			vert.clear();
		}
	}
	sort(ALL(ans));
	cout << SZ(ans) << '\n';
	for (auto [v, u] : ans)
		cout << v + 1 << ' ' << u + 1 << '\n';
	
	
	return 0;
}