#include <bits/stdc++.h>

using namespace std;

#define int long long
#define FOR(i, a, b) for(ll i = (a); i < (b); ++i)
#define FORR(i, a, b) for(ll i = (a); i > (b); --i)
#define REP(i, n) for(ll i = 0; i < (n); ++i)
#define REPR(i, n) for(ll i = n; i >= 0; i--)
#define FOREACH(x, a) for(auto &(x) : (a))
#define VECCIN(x)                                                              \
    for(auto &youso_ : (x)) cin >> youso_
#define bitcnt __builtin_popcount
#define SZ(x) ((ll)(x).size())
#define fi first
#define se second
#define All(a) (a).begin(), (a).end()
#define rAll(a) (a).rbegin(), (a).rend()
template <typename T = long long> inline T IN() {
    T x;
    cin >> x;
    return (x);
}
inline void CIN() {}
template <class Head, class... Tail>
inline void CIN(Head &&head, Tail &&... tail) {
    cin >> head;
    CIN(move(tail)...);
}
#define CCIN(...)                                                              \
    char __VA_ARGS__;                                                          \
    CIN(__VA_ARGS__)
#define DCIN(...)                                                              \
    double __VA_ARGS__;                                                        \
    CIN(__VA_ARGS__)
#define LCIN(...)                                                              \
    ll __VA_ARGS__;                                                            \
    CIN(__VA_ARGS__)
#define SCIN(...)                                                              \
    string __VA_ARGS__;                                                        \
    CIN(__VA_ARGS__)
#define Yes(a) cout << (a ? "Yes" : "No") << "\n"
#define YES(a) cout << (a ? "YES" : "NO") << "\n"
#define Printv(v)                                                              \
    {                                                                          \
        FOREACH(x, v) { cout << x << " "; }                                    \
        cout << "\n";                                                          \
    }
template <typename T = string> inline void eputs(T s) {
    cout << s << "\n";
    exit(0);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
    std::fill((T *)array, (T *)(array + N), val);
}
template <typename T> using PQG = priority_queue<T, vector<T>, greater<T>>;
template <typename T> using PQ = priority_queue<T>;

typedef long long ll;
typedef pair<ll, ll> PL;
typedef vector<PL> VPL;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef vector<double> VD;

const int INF = 1e9;
// const int MOD = 1e9 + 7;
const int MOD = 998244353;
const ll LINF = 1e18;
const double PI = atan(1.0) * 4.0;
const ll dx[] = {1, 1, 0, -1, -1, -1, 0, 1};
const ll dy[] = {0, 1, 1, 1, 0, -1, -1, -1};
#define PI 3.141592653589793238

ll N, M;
vector<multiset<ll>> G(100010);
VVL ans(100100);
vector<bool> used(100100, false);
map<PL, ll> eidx;

ll dfs(ll now, ll par) {
    ll p1 = -1;
    while(G[now].size()) {
        ll x = *G[now].begin();
        G[now].erase(x);
        G[x].erase(now);
        ll p2 = dfs(x, now);
        if(p2 != -1) {
            if(p1 == -1)
                p1 = p2;
            else {
                ans[now].emplace_back(p1);
                ans[now].emplace_back(p2);
                p1 = -1;
            }
        }
    }
    if(p1 != -1) {
        if(par != -1) {
            ans[now].emplace_back(p1);
            ans[now].emplace_back(par);
            return -1;
        }
    }
    return now;
}

signed main() {
    cin >> N >> M;
    if(M % 2) eputs(-1);
    REP(i, M) {
        LCIN(A, B);
        A--, B--;
        G[A].insert(B);
        G[B].insert(A);
        eidx[{A, B}] = eidx[{B, A}] = i;
    }
    dfs(0, -1);
    REP(i, N)
    REP(j, ans[i].size()) cout << i + 1 << " " << ans[i][j] + 1 << "\n";
}

Measured memory_bytes: 37376