//start of jonathanirvings' template v3.0.3 (BETA)

#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
typedef pair<int,int> pii;
typedef pair<LL,LL> pll;
typedef pair<string,string> pss;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vii;
typedef vector<LL> vl;
typedef vector<vl> vvl;

double EPS = 1e-9;
int INF = 1000000005;
long long INFF = 1000000000000000005LL;
double PI = acos(-1);
int dirx[8] = {-1,0,0,1,-1,-1,1,1};
int diry[8] = {0,1,-1,0,-1,1,-1,1};

#ifdef TESTING
  #define DEBUG fprintf(stderr,"====TESTING====\n")
  #define VALUE(x) cerr << "The value of " << #x << " is " << x << endl
  #define debug(...) fprintf(stderr, __VA_ARGS__)
#else
  #define DEBUG 
  #define VALUE(x)
  #define debug(...)
#endif

#define FOR(a,b,c) for (int (a)=(b);(a)<(c);++(a))
#define FORN(a,b,c) for (int (a)=(b);(a)<=(c);++(a))
#define FORD(a,b,c) for (int (a)=(b);(a)>=(c);--(a))
#define FORSQ(a,b,c) for (int (a)=(b);(a)*(a)<=(c);++(a))
#define FORC(a,b,c) for (char (a)=(b);(a)<=(c);++(a))
#define FOREACH(a,b) for (auto &(a) : (b))
#define REP(i,n) FOR(i,0,n)
#define REPN(i,n) FORN(i,1,n)
#define MAX(a,b) a = max(a,b)
#define MIN(a,b) a = min(a,b)
#define SQR(x) ((LL)(x) * (x))
#define RESET(a,b) memset(a,b,sizeof(a))
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define ALL(v) v.begin(),v.end()
#define ALLA(arr,sz) arr,arr+sz
#define SIZE(v) (int)v.size()
#define SORT(v) sort(ALL(v))
#define REVERSE(v) reverse(ALL(v))
#define SORTA(arr,sz) sort(ALLA(arr,sz))
#define REVERSEA(arr,sz) reverse(ALLA(arr,sz))
#define PERMUTE next_permutation
#define TC(t) while(t--)

inline string IntToString(LL a){
  char x[100];
  sprintf(x,"%lld",a); string s = x;
  return s;
}

inline LL StringToInt(string a){
  char x[100]; LL res;
  strcpy(x,a.c_str()); sscanf(x,"%lld",&res);
  return res;
}

inline string GetString(void){
  char x[1000005];
  scanf("%s",x); string s = x;
  return s;
}

inline string uppercase(string s){
  int n = SIZE(s); 
  REP(i,n) if (s[i] >= 'a' && s[i] <= 'z') s[i] = s[i] - 'a' + 'A';
  return s;
}

inline string lowercase(string s){
  int n = SIZE(s); 
  REP(i,n) if (s[i] >= 'A' && s[i] <= 'Z') s[i] = s[i] - 'A' + 'a';
  return s;
}

inline void OPEN (string s) {
  #ifndef TESTING
  freopen ((s + ".in").c_str (), "r", stdin);
  freopen ((s + ".out").c_str (), "w", stdout);
  #endif
}

//end of jonathanirvings' template v3.0.3 (BETA)

const int NO_CARRY = -1;

int N, M;
vector<int> parent;
vector<vector<int>> adj;
vector<tuple<int, int, int>> answer;
vector<bool> visited;
vector<int> original;

int root(int x) {
  return parent[x] = (x == parent[x] ? x : root(parent[x]));
}

int dfs(int x) {
  visited[x] = true;
  int now = NO_CARRY;
  for (int y : adj[x]) {
    if (visited[y]) {
      continue;
    }
    int z = dfs(y);
    if (z == NO_CARRY) {
      if (now == NO_CARRY) {
        now = y;
      } else {
        answer.push_back(make_tuple(now, x, y));
        now = NO_CARRY;
      }
    } else {
      answer.push_back(make_tuple(x, y, z));
    }
  }
  return now;
}

int main() {
  int N, M;
  scanf("%d %d", &N, &M);

  if (M % 2 == 1)
  {
    puts("-1");
    return 0;
  }

  adj.resize(N + M);
  original.resize(N + M);
  parent.resize(N);
  for (int i = 0; i < N; ++i) {
    parent[i] = i;
    original[i] = i;
  }

  for (int i = 0; i < M; ++i) {
    int U, V;
    scanf("%d %d", &U, &V);
    --U; --V;
    if (root(U) == root(V)) {
      original[N] = V;
      V = N++;
    } else {
      parent[root(U)] = root(V);
    }
    adj[U].push_back(V);
    adj[V].push_back(U);
  }

  visited.resize(N, false);
  for (int i = 0; i < N; ++i) {
    if (visited[i]) {
      continue;
    }
    dfs(i);
  }
  // printf("%d\n", answer.size());
  // for (int i = 0; i < answer.size(); ++i) {
  //   printf("%d %d %d\n",
  //     original[get<0>(answer[i])] + 1,
  //     original[get<1>(answer[i])] + 1,
  //     original[get<2>(answer[i])] + 1);
  // }
  for (int i = 0; i < answer.size(); ++i) {
      printf("%d %d\n", original[get<1>(answer[i])] + 1, original[get<0>(answer[i])] + 1);
      printf("%d %d\n", original[get<1>(answer[i])] + 1, original[get<2>(answer[i])] + 1);
  }
}












Measured memory_bytes: 17784