#include <bits/stdc++.h>
#define LLI long long int
#define FOR(v, a, b) for(LLI v = (a); v < (b); ++v)
#define FORE(v, a, b) for(LLI v = (a); v <= (b); ++v)
#define REP(v, n) FOR(v, 0, n)
#define REPE(v, n) FORE(v, 0, n)
#define REV(v, a, b) for(LLI v = (a); v >= (b); --v)
#define ALL(x) (x).begin(), (x).end()
#define RALL(x) (x).rbegin(), (x).rend()
#define ITR(it, c) for(auto it = (c).begin(); it != (c).end(); ++it)
#define RITR(it, c) for(auto it = (c).rbegin(); it != (c).rend(); ++it)
#define EXIST(c,x) ((c).find(x) != (c).end())
#define fst first
#define snd second
#define popcount __builtin_popcount
#define UNIQ(v) (v).erase(unique(ALL(v)), (v).end())
#define bit(i) (1LL<<(i))

#ifdef DEBUG
#include <misc/C++/Debug.cpp>
#else
#define dump(...) ((void)0)
#endif

#define gcd __gcd

using namespace std;
template <class T> constexpr T lcm(T m, T n){return m/gcd(m,n)*n;}

template <typename I> void join(ostream &ost, I s, I t, string d=" "){for(auto i=s; i!=t; ++i){if(i!=s)ost<<d; ost<<*i;}ost<<endl;}
template <typename T> istream& operator>>(istream &is, vector<T> &v){for(auto &a : v) is >> a; return is;}
template <typename T, typename U> istream& operator>>(istream &is, pair<T,U> &p){is >> p.first >> p.second; return is;}

template <typename T, typename U> bool chmin(T &a, const U &b){return (a>b ? a=b, true : false);}
template <typename T, typename U> bool chmax(T &a, const U &b){return (a<b ? a=b, true : false);}
template <typename T, size_t N, typename U> void fill_array(T (&a)[N], const U &v){fill((U*)a, (U*)(a+N), v);}



template <typename Cost = int> class Edge{
public:
  int from,to;
  Cost cost;
  Edge() {}
  Edge(int to, Cost cost): to(to), cost(cost){}
  Edge(int from, int to, Cost cost): from(from), to(to), cost(cost){}

  Edge rev() const {return Edge(to,from,cost);}
  
  friend ostream& operator<<(ostream &os, const Edge &e){
    os << "(FROM: " << e.from << "," << "TO: " << e.to << "," << "COST: " << e.cost << ")";
    return os;
  }
};

template <typename T> using Graph = vector<vector<Edge<T>>>;
template <typename T> using Tree = vector<vector<Edge<T>>>;

template <typename C, typename T> void add_edge(C &g, int from, int to, T w){
  g[from].push_back(Edge<T>(from, to, w));  
}

template <typename C, typename T> void add_undirected(C &g, int a, int b, T w){
  g[a].push_back(Edge<T>(a, b, w));
  g[b].push_back(Edge<T>(b, a, w));
}

void dfs(Graph<int> &g, int cur, int par, map<pair<int,int>,int> &dir, vector<bool> &visit){
  visit[cur] = true;


  int k = 0;
  for(auto &e : g[cur]){
    if(e.to == par) continue;

    if(!visit[e.to]){
      dfs(g,e.to,cur,dir,visit);
    }

    if(dir[{e.from,e.to}] == 1){
      ++k;
    }
  }
  
  for(auto &e : g[cur]){
    if(e.to == par){
      dir[{e.from,e.to}] = k%2!=0;
      dir[{e.to,e.from}] = k%2==0;
      break;
    }
  }
}



int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n,m;
  while(cin >> n >> m){
    Graph<int> g(n);
    map<pair<int,int>,int> dir;

    REP(i,m){
      int u,v; cin >> u >> v;
      --u,--v;
      add_undirected(g,u,v,1);

      dir[{u,v}] = 1;
      dir[{v,u}] = 0;
    }

    if(m%2==1){
      cout << -1 << endl;
    }else{
      vector<bool> visit(n);
      dfs(g,0,-1,dir,visit);

      for(auto &kv : dir){
        if(kv.snd){
          auto &p = kv.fst;
          cout << p.fst+1 << " " << p.snd+1 << endl;
        }
      }
    }
  }
  
  return 0;
}


Measured memory_bytes: 33408