#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 20;
bool visited[maxn];
int n, m, a, b, outDegree[maxn], dis[maxn];
vector<int> graph[maxn];
void dfs(int i) {
  visited[i] = 1;
  for (int x : graph[i]) {
    if (!visited[x]) {
      dis[x] = dis[i] + 1;
      dfs(x);
    }
    if (dis[x] > dis[i]) {
      if (outDegree[x] % 2 == 0) {
        outDegree[i]++;
        cout << i << " " << x << endl;
      } else {
        outDegree[x]++;
        cout << x << ' ' << i << endl;
      }
    }
  }
}
int main() {
  int n, m;
  cin >> n >> m;
  if (m % 2 == 1) return cout << -1 << endl, 0;
  for (int i = 0; i < m; i++) {
    cin >> a >> b;
    graph[a].push_back(b);
    graph[b].push_back(a);
  }
  dfs(1);
}
