#include <bits/stdc++.h>
using namespace std;
vector<pair<int, int> > v[1000002];
vector<pair<int, int> > Edge;
vector<int> e;
int n, m, k, d[1000002];
bool ok[1000000 + 100002], viz[2000002], vizN[1000002];
vector<pair<int, int> > ans;
void ciclu(int x) {
  while (!v[x].empty()) {
    int p = v[x].back().second;
    int vecin = v[x].back().first;
    v[x].pop_back();
    if (!viz[p]) {
      viz[p] = 1;
      ciclu(vecin);
    }
  }
  vizN[x] = 1;
  e.push_back(x);
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int x, y;
    cin >> x >> y;
    v[x].push_back({y, i});
    v[y].push_back({x, i});
    d[x]++;
    d[y]++;
  }
  int mm = m;
  for (int i = 1; i <= n; i++) {
    if (d[i] % 2) {
      v[i].push_back({0, ++mm});
      v[0].push_back({i, mm});
    }
  }
  for (int j = 0; j <= n; j++) {
    if (!vizN[j]) {
      e.clear();
      Edge.clear();
      ciclu(j);
      m = e.size() - 1;
      for (int i = 0; i < m; i++) {
        Edge.push_back({(int)e[i], (int)e[i + 1]});
      }
      for (int i = 0; i < Edge.size(); i++) {
        if (i % 2 == 1) {
          if (Edge[i].first == 0 || Edge[i].second == 0) continue;
          int t = (i - 1 + m) % m;
          if (Edge[t].first == 0 || Edge[t].second == 0) {
            ans.push_back(Edge[i]);
            continue;
          }
          t = (i + 1) % m;
          if (Edge[t].first == 0 || Edge[t].second == 0) {
            ans.push_back(Edge[i]);
            continue;
          }
        } else {
          if (Edge[i].first != 0 && Edge[i].second != 0) ans.push_back(Edge[i]);
        }
      }
    }
  }
  cout << ans.size() << "\n";
  for (int i = 0; i < ans.size(); i++)
    cout << ans[i].first << " " << ans[i].second << "\n";
  return 0;
}
