#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < int(n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define reps(i, n) for (int i = 1; i <= int(n); i++)
#define rreps(i, n) for (int i = int(n); i >= 1; i--)
#define repc(i, n) for (int i = 0; i <= int(n); i++)
#define rrepc(i, n) for (int i = int(n); i >= 0; i--)
#define repi(i, a, b) for (int i = int(a); i < int(b); i++)
#define repic(i, a, b) for (int i = int(a); i <= int(b); i++)
#define repp(i, n) rep(i, n)
#define reppp(i, n) repp(i, n)
#define rrepp(i, n) rrep(i, n)
#define repss(i, n) reps(i, n)
#define repcc(i, n) repc(i, n)
#define repii(i, a, b) repi(i, a, b)
#define each(x, y) for (auto &x : y)
#define all(a) (a).begin(), (a).end()
#define bit(b) (1ll << (b))

using namespace std;

using i32 = int;
using i64 = long long;
using u64 = unsigned long long;
using f80 = long double;
using vi32 = vector<i32>;
using vi64 = vector<i64>;
using vu64 = vector<u64>;
using vf80 = vector<f80>;
using vstr = vector<string>;

inline void yes() { cout << "Yes" << '\n'; exit(0); }
inline void no() { cout << "No" << '\n'; exit(0); }
inline i64 gcd(i64 a, i64 b) { if (min(a, b) == 0) return max(a, b); if (a % b == 0) return b; return gcd(b, a % b); }
inline i64 lcm(i64 a, i64 b) { return a / gcd(a, b) * b; }
inline u64 xorshift() { static u64 x = 88172645463325252ull; x = x ^ (x << 7); return x = x ^ (x >> 9); }
void solve(); int main() { ios::sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(16); solve(); return 0; }
template <typename T> class pqasc : public priority_queue<T, vector<T>, greater<T>> {};
template <typename T> class pqdesc : public priority_queue<T, vector<T>, less<T>> {};
template <typename T> inline void amax(T &x, T y) { if (x < y) x = y; }
template <typename T> inline void amin(T &x, T y) { if (x > y) x = y; }
template <typename T> inline T power(T x, i64 n, T e = 1) { T r = e; while (n > 0) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; }
template <typename T> istream& operator>>(istream &is, vector<T> &v) { each(x, v) is >> x; return is; }
template <typename T> ostream& operator<<(ostream &os, vector<T> &v) { rep(i, v.size()) { if (i) os << ' '; os << v[i]; } return os; }
template <typename T, typename S> istream& operator>>(istream &is, pair<T, S> &p) { is >> p.first >> p.second; return is; }
template <typename T, typename S> ostream& operator<<(ostream &os, pair<T, S> &p) { os << p.first << ' ' << p.second; return os; }

struct UnWeightedGraph {
  struct Edge {
    int to, rev;
    bool used = false;
    Edge(int to, int rev) : to(to), rev(rev) {}
  };
  vector<vector<Edge>> edges;
  int n;
  UnWeightedGraph(int n) : n(n) {
    edges.assign(n, vector<Edge>());
  }
  void add_edge(int v, int u) {
    edges[v].emplace_back(u, (int) edges[u].size());
    edges[u].emplace_back(v, (int) edges[v].size() - 1);
  }
  vector<Edge> &operator[](int x) {
    return edges[x];
  }
};

void solve() {
  int N, M; cin >> N >> M;
  auto graph = UnWeightedGraph(N);
  rep(i, M) {
    int u, v; cin >> u >> v;
    u--, v--;
    graph.add_edge(u, v);
  }
  if (M % 2 == 1) {
    cout << -1 << '\n';
    return;
  }
  vector<bool> seen(N);
  vi32 cnt(N);
  vector<pair<int, int>> ans;
  function<void(int, int)> dfs = [&](int v, int p) {
    seen[v] = true;
    each(e, graph[v]) {
      if (e.to == p) continue;
      if (seen[e.to]) {
        if (e.used) continue;
        ans.emplace_back(v + 1, e.to + 1);
        e.used = graph[e.to][e.rev].used = true;
        cnt[v]++;
        continue;
      }
      dfs(e.to, v);
      e.used = graph[e.to][e.rev].used = true;
    }
    if (p == -1) return;
    if (cnt[v] % 2 == 0) {
      ans.emplace_back(p + 1, v + 1);
      cnt[p]++;
    } else {
      ans.emplace_back(v + 1, p + 1);
      cnt[v]++;
    }
  };
  dfs(0, -1);
  rep(i, M) cout << ans[i] << '\n';
}


Measured memory_bytes: 17524