#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const double eps = 1e-11;
const int oo = 0x3f3f3f3f;
template <class T>
inline void checkmin(T &a, T b) {
  if (b < a) a = b;
}
template <class T>
inline void checkmax(T &a, T b) {
  if (b > a) a = b;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
template <class T>
inline T lowbit(T n) {
  return (n ^ (n - 1)) & n;
}
template <class T>
inline int countbit(T n) {
  return (n == 0) ? 0 : (1 + countbit(n & (n - 1)));
}
template <class T>
inline T gcd(T a, T b) {
  T c;
  while (a != 0) {
    c = a;
    a = b % a;
    b = c;
  }
  return b;
}
template <class T>
inline T mabs(T a) {
  if (a < 0)
    return -a;
  else
    return a;
}
typedef vector<int> VI;
typedef vector<VI> VII;
typedef vector<string> VS;
#pragma comment(linker, "/STACK:36777216")
namespace FASTIO {
char outputbuffer[(10000) << 1], inputbuffer[(10000)];
char *outptr = outputbuffer, *ioptr = inputbuffer + (10000),
     *ioend = inputbuffer + (10000);
int input_eof = 0;
void init_input() {
  if (input_eof) return;
  int existing = (10000) - (ioend - inputbuffer);
  memcpy(inputbuffer, ioend, existing);
  int wanted = ioend - inputbuffer;
  int count = fread(inputbuffer + existing, 1, wanted, stdin);
  if (count < wanted) input_eof = 1;
  ioend = inputbuffer + (10000) - (wanted - count);
  while (*--ioend > ' ')
    ;
  ioend++;
  ioptr = inputbuffer;
}
inline void non_whitespace() {
  for (;;) {
    if (ioptr >= ioend) init_input();
    if (*ioptr > ' ') return;
    ioptr++;
  }
}
void flush_output() {
  fwrite(outputbuffer, 1, outptr - outputbuffer, stdout);
  outptr = outputbuffer;
}
inline int getint() {
  non_whitespace();
  int neg = 0;
  if (*ioptr == '-') {
    ioptr++;
    neg = 1;
  }
  int n = 0;
  while (*ioptr > ' ') n = (n << 3) + (n << 1) + *ioptr++ - '0';
  ioptr++;
  if (neg) n = -n;
  return n;
}
inline void putint(int n) {
  if (n < 0) {
    *outptr++ = '-';
    n = -n;
  }
  char buffer[10];
  int i = 0, n2;
  do {
    n2 = n / 10;
    buffer[i++] = n - (n2 << 3) - (n2 << 1) + '0';
  } while (n = n2);
  while (i) (*outptr++ = (buffer[--i]));
  (*outptr++ = ('\n'));
  flush_output();
}
};  // namespace FASTIO
const int N = (int)1e5 + 111;
const int M = (int)5e5 + 111;
const int MOD = (int)1e9 + 7;
VI g[N];
int odd[N], topoList[M], sz;
struct HASH {
  size_t operator()(const pair<int, int> &x) const {
    return ((long long)x.first + x.second) % MOD;
  }
};
struct EQUAL {
  bool operator()(const pair<int, int> &a, const pair<int, int> &b) const {
    return (a.first == b.first && a.second == b.second);
  }
};
unordered_map<pair<int, int>, int, HASH, EQUAL> cnt;
inline void topo(int from) {
  while (g[from].size() > 0) {
    int to = g[from].back();
    g[from].pop_back();
    int a = min(from, to);
    int b = max(from, to);
    if (a > b) a ^= b ^= a ^= b;
    if (cnt[make_pair(a, b)] > 0) {
      cnt[make_pair(a, b)]--;
      topo(to);
    }
  }
  topoList[sz++] = from;
}
inline int solve(int testnum) {
  int n = FASTIO::getint(), m = FASTIO::getint();
  cnt.clear();
  for (int i = (0); i < int(n); i++) {
    g[i].clear();
    odd[i] = 0;
  }
  for (int i = (0); i < int(m); i++) {
    int u = FASTIO::getint(), v = FASTIO::getint();
    if (u > v) u ^= v ^= u ^= v;
    g[u].push_back(v);
    g[v].push_back(u);
    cnt[make_pair(u, v)]++;
  }
  sz = 0;
  for (int i = (1); i < int(n + 1); i++)
    if (g[i].size() % 2) odd[sz++] = i;
  for (int i = 0; i < sz; i += 2) {
    int a = odd[i], b = odd[i + 1];
    if (a > b) a ^= b ^= a ^= b;
    g[a].push_back(b);
    g[b].push_back(a);
    cnt[make_pair(a, b)]++;
  }
  sz = 0;
  topo(1);
  if (sz % 2 == 0) {
    int last = topoList[sz - 1];
    topoList[sz++] = last;
  }
  --sz;
  printf("%d\n", sz);
  for (int i = (0); i < int(sz); i++) {
    if (i % 2)
      printf("%d %d\n", topoList[i], topoList[i + 1]);
    else
      printf("%d %d\n", topoList[i + 1], topoList[i]);
  }
  return 0;
}
int main(int argc, char *argv[]) {
  ios::sync_with_stdio(false);
  int t = 1;
  if (argc > 1) t = atoi(argv[1]);
  for (int _t = (1); _t < int(t + 1); _t++) {
    int ret = ::solve(_t);
    if (ret == -1) break;
    cerr << "Solved test #" << _t << endl;
  }
  return 0;
}
