#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <array>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <stack>
#include <queue>
#include <bitset>
#include <tuple>
#include <cmath>
#include <complex>
#include <algorithm>
#include <utility>
#include <regex>
#include <cstdint>
#include <numeric>
#include <functional>
#include <cassert>

using namespace std;
using ll = long long;
using ull = unsigned long long;

constexpr ll INF = 1'000'000'000'000'000'000;
namespace utils{
#define ALL(x) begin(x), end(x)
#define rALL(x) rbegin(x), rend(x)
    template<class T, class Compare> using p_queue = priority_queue<T, vector<T>, Compare>;
    template<class T> using min_queue = p_queue<T, greater<T>>;
    template<class T> using max_queue = p_queue<T, less<T>>;

    template<class T> bool min_update(T& X, const T& A){ if(X > A) {X = A; return true;} return false; }
    template<class T> bool max_update(T& X, const T& A){ if(X < A) {X = A; return true;} return false; }
    using V_Set = unordered_set<int>;
    using E_Set = unordered_map<int, V_Set>;

    ll operator"" _64(unsigned long long x){ return ll(x); }
    ull operator"" _64u(unsigned long long x){ return ull(x); }

    template<class T>
    vector<T> make_vector(int n, T t){
        return vector<T>(n, t);
    }
    template<class ...Ts>
    auto make_vector(int n, Ts ... ts){
        return vector<decltype(make_vector(ts...))>(n, make_vector(ts...));
    }

    template<class T>
    ostream& operator<<(ostream& os, const vector<T>& v){
        for (auto &&x : v) { os << x << ' '; } cout << endl; return os ;
    }
}
using namespace utils;

class solver{
    istream& is;
    ostream& os;

    E_Set outE, E;
    ll N, M;
    vector<bool> vis;
    vector<pair<int, int>> sE;

public:
    solver(istream& I, ostream& O) :is(I), os(O) {}

    void make_spanning(int v){
        vis[v] = true;
        for (auto &&u : E[v]) {
            if(vis[u]) { continue; }
            make_spanning(u);
            sE.emplace_back(v, u);
        } // end u
    }

    void run(){
        is >> N >> M;
        if(!is) return;
        for (int i = 0; i < M; ++i) {
            int A, B; is >> A >> B;
            E[A].insert(B); E[B].insert(A);
        } // end i
        vis.resize(N+1, false);
        if(M % 2) {
            cout << -1 << endl; return;
        }
        make_spanning(1);
        assert(sE.size() == N-1);

        for(auto&& p = sE.begin(); p != sE.end(); p++){
            int v, u;
            tie(v, u) = *p;
            for (auto &&t : E[u]) {
                if(t == v) continue;
                outE[t].insert(u);
                E[t].erase(u);
            } // end t
            E[v].erase(u);
            E.erase(u);
            if(outE[u].size() % 2){
                outE[u].insert(v);
            }
            else{
                outE[v].insert(u);
            }
        }
        for (auto &&et : outE) {
            int u = et.first;
            for (auto &&v : et.second) {
                cout << u << ' ' << v << endl;
            } // end v
        } // end et
    }
};

int main(int argc, char *argv[]) {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << setprecision(16) << scientific;
#ifdef DEBUG
    string test_cases = "test_EvenDegrees.txt";
    cerr << test_cases << " -->" << endl;
    auto fs = fstream(test_cases, fstream::in);
    int loop = 0;
    while(fs) {
        loop++;
        cout << '#' << loop << "#------\n";
        solver(fs, cout).run();
    }
    if(loop <= 1) {
        cout << "===" << endl;
        while(cin) solver(cin, cout).run();
    }
#else
    solver(cin, cout).run();
#endif
    return 0;
}


Measured memory_bytes: 26592