#include <bits/stdc++.h>

using namespace std;
using ll = long long;
// #define int ll
using PII = pair<ll, ll>;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()

template<typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }

template<typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type
fill_v(T &t, const V &v) { t=v; }
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t, const V &v ) { for(auto &e:t) fill_v(e,v); }

template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a) {
    out<<'('<<a.first<<','<<a.second<<')'; return out;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
    out<<'[';
    for(const T &i: a) out<<i<<',';
    out<<']';
    return out;
}
template<class T>
ostream &operator <<(ostream& out, const set<T>& a) {
    out<<'{';
    for(const T &i: a) out<<i<<',';
    out<<'}';
    return out;
}
template<class T, class S>
ostream &operator <<(ostream& out, const map<T,S>& a) {
    out<<'{';
    for(auto &i: a) out<<i<<',';
    out<<'}';
    return out;
}

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0}; // DRUL
const int INF = 1<<30;
const ll LLINF = 1LL<<60;
const ll MOD = 1000000007;

struct UnionFind {
    vector<int> par, s;
    UnionFind(int n=2e5) { init(n); }
    void init(int n) {
        s.assign(n, 1); par.resize(n);
        iota(par.begin(), par.end(), 0);
    }
    int find(int x) {
        if(par[x] == x) return x;
        return par[x] = find(par[x]);
    }
    void unite(int x, int y) {
        x = find(x);
        y = find(y);
        if(x == y) return;
        if(s[x] < s[y]) par[x] = y, s[y] = s[x] + s[y];
        else par[y] = x, s[x] = s[x] + s[y];
    }
    bool same(int x, int y) { return find(x) == find(y); }
    int size(int x) { return s[find(x)]; }
};

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

    ll n, m;
    cin >> n >> m;
    vector<ll> c(m), d(m);
    REP(i, m) cin >> c[i] >> d[i], c[i]--, d[i]--;

    if(m%2) {
        cout << -1 << endl;
        return 0;
    }

    // 全域木をつくる
    vector<vector<ll>> g(n);
    vector<ll> h(n);
    vector<PII> ans;
    UnionFind uf(n);
    REP(i, m) {
        if(uf.same(c[i], d[i])) {
            ans.push_back({c[i], d[i]});
            (h[c[i]] += 1) %= 2;
        } else {
            uf.unite(c[i], d[i]);
            g[c[i]].push_back(d[i]);
            g[d[i]].push_back(c[i]);
        }
    }

    function<void(ll, ll)> dfs = [&](ll v, ll p) {
        for(auto to: g[v]) {
            if(to == p) continue;
            dfs(to, v);
            if(h[to] == 0) {
                ans.push_back({v, to});
                (h[v] += 1) %= 2;
            } else {
                ans.push_back({to, v});
                (h[to] += 1) %= 2;
            }
        }
    };
    dfs(0, -1);

    for(auto p: ans) cout << p.first+1 << " " << p.second+1 << endl;

    return 0;
}


Measured memory_bytes: 20976