// https://atcoder.jp/contests/agc035/tasks/agc035_b
//
#![allow(unused_imports)]
use std::io::*;
use std::io::Write;
use std::fmt::*;
use std::str::*;
use std::cmp::*;
use std::collections::*;

// Input macros.
// Original by tanakh: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };

    ($iter:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, [ next / $t:tt ]) => {
        {
            let len = read_value!($iter, usize);
            (0..len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
        }
    };

    ($iter:expr, switch) => {
        {
            let ty = read_value!($iter, i32);
            if ty == 1 {
                vec![ty, read_value!($iter, i32), read_value!($iter, i32)]
            } else if ty == 2 {
                vec![ty, read_value!($iter, i32)]
            } else {
                vec![ty, read_value!($iter, i32)]
            }
        }
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

#[allow(unused_macros)]
macro_rules! read_line {
    ($t:tt) => {
        {
            let mut s = String::new();
            std::io::stdin().read_line(&mut s).unwrap();
            s.trim_right().parse::<$t>().unwrap()
        }
    }
}

#[allow(unused_macros)]
macro_rules! dvec {
    ($t:expr ; $len:expr) => {
        vec![$t; $len]
    };

    ($t:expr ; $len:expr, $($rest:expr),*) => {
        vec![dvec!($t; $($rest),*); $len]
    };
}

#[allow(unused_macros)]
macro_rules! ifv {
    ($t:expr, $a:expr, $b: expr) => {
        if $t { $a } else { $b }
    }
}

#[allow(unused_macros)]
macro_rules! fill {
    ($t:expr, $v:expr) => {
        for i in 0..$t.len() {
            $t[i] = $v;
        }
    };
}

#[allow(unused_macros)]
macro_rules! join {
    ($t:expr, $glue:expr) => {
        $t.into_iter().map(|w| w.to_string()).collect::<Vec<_>>().join($glue)
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        println!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
    }
}

// ===

struct UnionFind {
      n: usize,
      parent: Vec<usize>,
      count: Vec<usize>
}

impl UnionFind {
     fn new(n: usize) -> Self {
           let mut p = vec![0; n];
           for i in 0..n {
                 p[i] = i;
           }
           UnionFind { n: n, parent: p, count: vec![1; n] }
     }

     fn find(&mut self, a: usize) -> usize {
           if self.parent[a] == a {
                 return a;
           }
           let par = self.parent[a];
           self.parent[a] = self.find(par);
           self.parent[a]
     }

     fn unite(&mut self, a: usize, b: usize) {
           let a = self.find(a);
           let b = self.find(b);
           if a == b {
                 return;
           }
           let ca = self.count[a];
           let cb = self.count[b];
           let total = ca + cb;
           self.count[b] = total;
           self.count[a] = total;
           if ca < cb {
                 self.parent[a] = b;
           } else {
                 self.parent[b] = a;
           }
     }

     fn same(&mut self, a: usize, b: usize) -> bool {
           self.find(a) == self.find(b)
     }

     fn count(&mut self, a: usize) -> usize {
           let a = self.find(a);
           self.count[a]
     }
}

type Graph = Vec<Vec<usize>>;

fn dfs_cpo(g: &Graph, root: usize) -> (Vec<usize>, Vec<Option<usize>>, Vec<usize>) {
    let n = g.len();
    struct Cpo {
        count: Vec<usize>,
        parent: Vec<Option<usize>>,
        order: Vec<usize>,
        oidx: usize
    };
    let mut cpo = Cpo {
        count: vec![0; n],
        parent: vec![None; n],
        order: vec![0; n],
        oidx: 0
    };

    fn dfs(g: &Graph, now: usize, par: Option<usize>, cpo: &mut Cpo) {
        for &to in &g[now] {
            if Some(to) != par {
                dfs(g, to, Some(now), cpo);
            }
        }
        cpo.count[now] = 1;
        for &to in &g[now] {
            if Some(to) != par {
                cpo.count[now] += cpo.count[to];
            }
        }
        cpo.parent[now] = par;
        cpo.order[cpo.oidx] = now;
        cpo.oidx += 1;

    }
    dfs(&g, root, None, &mut cpo);
    (cpo.count, cpo.parent, cpo.order)
}
//===

fn main() {
    input! {
        n: usize, m: usize,
        edges: [(usize1, usize1); m]
    };
    if m % 2 == 1 {
        println!("-1");
        return;
    }

    let mut uf = UnionFind::new(n);
    let mut tree = vec![vec![]; n];
    let mut deg = vec![0; n];
    let mut ans = vec![];

    let mut edgemap = HashMap::new();
    for (idx, &(u,v)) in edges.iter().enumerate() {
        if uf.same(u, v) {
            deg[u] += 1;
            ans.push((u+1, v+1));
        } else {
            uf.unite(u, v);
            tree[u].push(v);
            tree[v].push(u);
            edgemap.insert((u,v), idx);
            edgemap.insert((v,u), idx);
        }
    }

    let mut visited = vec![0; m];
    let (count, parent, order) = dfs_cpo(&tree, 0);
    for i in 0..n {
        let v = order[i];
        let mut peid = m;
        for &to in &tree[v] {
            let eid = *edgemap.get(&(v, to)).unwrap();
            if visited[eid] != 0 {
                continue;
            }
            if Some(to) == parent[v] {
                peid = eid;
            } else {
                deg[v] += 1;
                ans.push((v+1, to+1));
                visited[eid] = ifv!(v < to, 1, -1);
            }
        }
        if let Some(p) = parent[v] {
            if deg[v] % 2 == 1 {
                deg[v] += 1;
                ans.push((v+1, p+1));
                visited[peid] = ifv!(v < p, 1, -1);
            }
        } else {
            assert!(i == n-1, deg[v] % 2 == 0);
        }
    }

    for &(u, v) in &ans {
        println!("{} {}", u, v);
    }

}


Measured memory_bytes: 42076