#include <bits/stdc++.h>
using namespace std;
int to[500005], tot, node[500005], st[500005], hd, ve[500005], d[500005],
    val[500005], nxt[500005], siz[500005];
void add(int x, int y, int v) {
  to[++tot] = y;
  nxt[tot] = node[x];
  node[x] = tot;
  val[tot] = v;
}
void dfs(int now) {
  int j = -1;
  for (int &i = node[now]; i; i = nxt[i]) {
    if (!ve[val[i]]) {
      j = i;
      ve[val[i]] = 1;
      dfs(to[i]);
      break;
    }
  }
  if (j == -1) return;
  st[++hd] = to[j];
  while (node[now]) {
    for (int &i = node[now]; i; i = nxt[i]) {
      if (!ve[val[i]]) {
        j = i;
        ve[val[j]] = 1;
        dfs(to[i]);
        st[++hd] = to[j];
        break;
      }
    }
  }
}
int las, n, m, i, x, y;
int main() {
  for (cin >> n >> m, i = 1; i <= m; ++i)
    cin >> x >> y, add(x, y, i), add(y, x, i), d[x] ^= 1, d[y] ^= 1;
  for (i = 1; i <= n; ++i)
    if (d[i]) {
      if (las)
        add(las, i, ++m), add(i, las, m), las = 0;
      else
        las = i;
    }
  if (m & 1) add(n, n, ++m);
  dfs(1);
  st[++hd] = 1;
  cout << m << "\n";
  for (i = 1; i <= m; ++i)
    if (i & 1)
      cout << st[i] << " " << st[i + 1] << "\n";
    else
      cout << st[i + 1] << " " << st[i] << '\n';
}
