#include <bits/stdc++.h>
using namespace std;
void Main();
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  while (~cin.peek()) Main(), cin.get();
  return 0;
}
void Main() {
  int n, m;
  cin >> n >> m;
  vector<pair<int, int>> edge(m);
  vector<set<int>> graph(n);
  for (int i = 0; i < m; i++) {
    int u, v;
    cin >> u >> v;
    u--;
    v--;
    graph[u].insert(i);
    graph[v].insert(i);
    edge[i] = {u, v};
  }
  vector<int> ans;
  function<void(int, int, int)> dfs = [&](int cur, int laste, int even) {
    if (~laste) {
      graph[cur].erase(laste);
      if (even || graph[cur].size() == 0) ans.push_back(laste);
      if (!graph[cur].size()) return;
    }
    int e = *graph[cur].begin();
    graph[cur].erase(e);
    dfs(edge[e].first ^ edge[e].second ^ cur, e, even ^ 1);
  };
  for (int i = 0; i < n; i++) {
    if (graph[i].size() & 1) dfs(i, -1, 0);
  }
  for (int i = 0; i < n; i++) {
    if (graph[i].size()) dfs(i, -1, 0);
  }
  cout << ans.size() << endl;
  for (int &e : ans) {
    cout << edge[e].first + 1 << " " << edge[e].second + 1 << endl;
  }
}
