#include <bits/stdc++.h>
using namespace std;
vector<pair<int, int> > g[400010];
int deg[400010];
vector<int> rlt;
bool vis[400010];
int head[400010];
void dfs(int k) {
  while (head[k] < g[k].size()) {
    int i = head[k]++;
    if (!vis[g[k][i].second]) {
      vis[g[k][i].second] = 1;
      dfs(g[k][i].first);
      rlt.push_back(g[k][i].first);
    }
  }
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int x, y;
    cin >> x >> y;
    g[x].emplace_back(y, i);
    g[y].emplace_back(x, i);
    deg[x]++, deg[y]++;
  }
  vector<int> odd;
  for (int i = 1; i <= n; i++)
    if (deg[i] & 1) odd.push_back(i);
  int e = m;
  for (int i = 0; i < odd.size(); i += 2) {
    int x = odd[i], y = odd[i + 1];
    e++;
    g[x].emplace_back(y, e);
    g[y].emplace_back(x, e);
  }
  if (e & 1) {
    e++;
    g[1].emplace_back(1, e);
    g[1].emplace_back(1, e);
  }
  dfs(1);
  cout << rlt.size() << endl;
  for (int i = 0; i < rlt.size(); i += 2) {
    cout << rlt[i] << " " << rlt[i + 1] << endl;
  }
  rlt.push_back(rlt[0]);
  for (int i = 1; i < rlt.size(); i += 2) {
    cout << rlt[i + 1] << " " << rlt[i] << endl;
  }
  return 0;
}
