import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.complex, std.container, std.math, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


int N, M;
int[] A, B;

int[][] G;

void main() {
  try {
    for (; ; ) {
      N = readInt();
      M = readInt();
      A = new int[M];
      B = new int[M];
      foreach (i; 0 .. M) {
        A[i] = readInt() - 1;
        B[i] = readInt() - 1;
      }
      
      if (M % 2 == 0) {
        auto deg = new int[N];
        auto cnt = new int[N];
        auto sets = new RedBlackTree!int[N];
        foreach (u; 0 .. N) {
          sets[u] = new RedBlackTree!int;
        }
        foreach (i; 0 .. M) {
          ++deg[A[i]];
          ++deg[B[i]];
          sets[A[i]].insert(B[i]);
          sets[B[i]].insert(A[i]);
        }
        alias Entry = Tuple!(int, int);
        BinaryHeap!(Array!Entry, "a > b") q;
        auto vis = new bool[N];
        foreach (u; 0 .. N) {
          if (deg[u] > 0) {
            q.insert(Entry(deg[u], -u));
          }
        }
        for (; !q.empty; ) {
          int u = -q.front[1];
          q.removeFront;
          if (deg[u] > 0) {
            int v = sets[u].front;
            if (deg[u] == 1) {
              if (cnt[u] % 2 == 0) {
                swap(u, v);
              }
            }
            writeln(u + 1, " ", v + 1);
            --deg[u];
            --deg[v];
            ++cnt[u];
            sets[u].removeKey(v);
            sets[v].removeKey(u);
            if (deg[u] > 0) {
              q.insert(Entry(deg[u], -u));
            }
            if (deg[v] > 0) {
              q.insert(Entry(deg[v], -v));
            }
          }
        }
      } else {
        writeln(-1);
      }
    }
  } catch (EOFException e) {
  }
}
