pub trait IterScan: Sized {
    type Output;
    fn scan<'a, I: Iterator<Item = &'a str>>(iter: &mut I) -> Option<Self::Output>;
}
pub trait MarkedIterScan: Sized {
    type Output;
    fn mscan<'a, I: Iterator<Item = &'a str>>(self, iter: &mut I) -> Option<Self::Output>;
}
#[derive(Debug)]
pub struct Scanner<'a> {
    iter: std::str::SplitAsciiWhitespace<'a>,
}
impl<'a> Scanner<'a> {
    #[inline]
    pub fn new(s: &'a str) -> Self {
        let iter = s.split_ascii_whitespace();
        Self { iter }
    }
    #[inline]
    pub fn scan<T: IterScan>(&mut self) -> <T as IterScan>::Output {
        T::scan(&mut self.iter).unwrap()
    }
    #[inline]
    pub fn mscan<T: MarkedIterScan>(&mut self, marker: T) -> <T as MarkedIterScan>::Output {
        marker.mscan(&mut self.iter).unwrap()
    }
    #[inline]
    pub fn scan_vec<T: IterScan>(&mut self, size: usize) -> Vec<<T as IterScan>::Output> {
        (0..size)
            .map(|_| T::scan(&mut self.iter).unwrap())
            .collect()
    }
    #[inline]
    pub fn scan_chars(&mut self) -> Vec<char> {
        self.iter.next().unwrap().chars().collect::<Vec<char>>()
    }
    #[inline]
    pub fn scan_chars_with(&mut self, base: char) -> Vec<usize> {
        self.iter
            .next()
            .unwrap()
            .chars()
            .map(|c| (c as u8 - base as u8) as usize)
            .collect::<Vec<usize>>()
    }
}
mod scanner_impls {
    use super::*;
    macro_rules !iter_scan_impls {($($t :ty ) *) =>{$(impl IterScan for $t {type Output =Self ;#[inline ] fn scan <'a ,I :Iterator <Item =&'a str >>(iter :&mut I ) ->Option <Self >{iter .next () ?.parse ::<$t >() .ok () } } ) *} ;}
    iter_scan_impls !(char u8 u16 u32 u64 usize i8 i16 i32 i64 isize f32 f64 u128 i128 String ) ;
    macro_rules !iter_scan_tuple_impl {($($T :ident ) *) =>{impl <$($T :IterScan ) ,*>IterScan for ($($T ,) *) {type Output =($(<$T as IterScan >::Output ,) *) ;#[inline ] fn scan <'a ,It :Iterator <Item =&'a str >>(_iter :&mut It ) ->Option <Self ::Output >{Some (($($T ::scan (_iter ) ?,) *) ) } } } ;}
    iter_scan_tuple_impl!();
    iter_scan_tuple_impl!(A);
    iter_scan_tuple_impl !(A B ) ;
    iter_scan_tuple_impl !(A B C ) ;
    iter_scan_tuple_impl !(A B C D ) ;
    iter_scan_tuple_impl !(A B C D E ) ;
    iter_scan_tuple_impl !(A B C D E F ) ;
    iter_scan_tuple_impl !(A B C D E F G ) ;
    iter_scan_tuple_impl !(A B C D E F G H ) ;
    iter_scan_tuple_impl !(A B C D E F G H I ) ;
    iter_scan_tuple_impl !(A B C D E F G H I J ) ;
    iter_scan_tuple_impl !(A B C D E F G H I J K ) ;
    pub struct ScannerIter<'a, 'b, T> {
        inner: &'b mut Scanner<'a>,
        _marker: std::marker::PhantomData<fn() -> T>,
    }
    impl<'a, 'b, T: IterScan> Iterator for ScannerIter<'a, 'b, T> {
        type Item = <T as IterScan>::Output;
        fn next(&mut self) -> Option<Self::Item> {
            T::scan(&mut self.inner.iter)
        }
    }
    impl<'a> Scanner<'a> {
        #[inline]
        pub fn iter<'b, T: IterScan>(&'b mut self) -> ScannerIter<'a, 'b, T> {
            ScannerIter {
                inner: self,
                _marker: std::marker::PhantomData,
            }
        }
    }
}
pub mod marker {
    use super::*;
    pub struct Usize1;
    impl IterScan for Usize1 {
        type Output = usize;
        #[inline]
        fn scan<'a, I: Iterator<Item = &'a str>>(iter: &mut I) -> Option<Self::Output> {
            usize::scan(iter).map(|x| x.wrapping_sub(1))
        }
    }
    pub struct Isize1;
    impl IterScan for Isize1 {
        type Output = isize;
        #[inline]
        fn scan<'a, I: Iterator<Item = &'a str>>(iter: &mut I) -> Option<Self::Output> {
            isize::scan(iter).map(|x| x.wrapping_sub(1))
        }
    }
}
#[macro_export]
macro_rules !min {($e :expr ) =>{$e } ;($e :expr ,$($es :expr ) ,+) =>{std ::cmp ::min ($e ,min !($($es ) ,+) ) } ;}
#[macro_export]
macro_rules !chmin {($dst :expr ,$($src :expr ) ,+) =>{{let x =std ::cmp ::min ($dst ,min !($($src ) ,+) ) ;$dst =x ;} } ;}
#[macro_export]
macro_rules !max {($e :expr ) =>{$e } ;($e :expr ,$($es :expr ) ,+) =>{std ::cmp ::max ($e ,max !($($es ) ,+) ) } ;}
#[macro_export]
macro_rules !chmax {($dst :expr ,$($src :expr ) ,+) =>{{let x =std ::cmp ::max ($dst ,max !($($src ) ,+) ) ;$dst =x ;} } ;}
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct Adjacent {
    pub id: usize,
    pub to: usize,
}
impl Adjacent {
    pub fn new(id: usize, to: usize) -> Adjacent {
        Adjacent { id, to }
    }
}
#[derive(Clone, Debug, Default)]
pub struct Graph {
    pub vsize: usize,
    pub esize: usize,
    pub graph: Vec<Vec<Adjacent>>,
}
impl Graph {
    pub fn new(vsize: usize) -> Graph {
        Graph {
            vsize,
            esize: 0,
            graph: vec![vec![]; vsize],
        }
    }
    pub fn add_edge(&mut self, from: usize, to: usize) {
        self.graph[from].push(Adjacent::new(self.esize, to));
        self.esize += 1;
    }
    pub fn add_undirected_edge(&mut self, u: usize, v: usize) {
        self.graph[u].push(Adjacent::new(self.esize, v));
        self.graph[v].push(Adjacent::new(self.esize, u));
        self.esize += 1;
    }
    pub fn vertices(&self) -> std::ops::Range<usize> {
        0..self.vsize
    }
    pub fn adjacency(&self, from: usize) -> &Vec<Adjacent> {
        &self.graph[from]
    }
    pub fn eid_cache(&self) -> GraphEidCache<'_> {
        let mut cache = vec![(0, 0); self.esize];
        for u in self.vertices() {
            for a in self.adjacency(u) {
                cache[a.id] = (u, a.to);
            }
        }
        GraphEidCache { graph: self, cache }
    }
}
pub struct GraphScanner<U: IterScan<Output = usize>, T: IterScan> {
    vsize: usize,
    esize: usize,
    directed: bool,
    _marker: std::marker::PhantomData<fn() -> (U, T)>,
}
impl<U: IterScan<Output = usize>, T: IterScan> GraphScanner<U, T> {
    pub fn new(vsize: usize, esize: usize, directed: bool) -> Self {
        Self {
            vsize,
            esize,
            directed,
            _marker: std::marker::PhantomData,
        }
    }
}
impl<U: IterScan<Output = usize>, T: IterScan> MarkedIterScan for GraphScanner<U, T> {
    type Output = (Graph, Vec<<T as IterScan>::Output>);
    fn mscan<'a, I: Iterator<Item = &'a str>>(self, iter: &mut I) -> Option<Self::Output> {
        let mut graph = Graph::new(self.vsize);
        let mut rest = Vec::with_capacity(self.esize);
        for _ in 0..self.esize {
            let (from, to) = (U::scan(iter)?, U::scan(iter)?);
            if self.directed {
                graph.add_edge(from, to);
            } else {
                graph.add_undirected_edge(from, to);
            }
            rest.push(T::scan(iter)?);
        }
        Some((graph, rest))
    }
}
#[derive(Debug, Clone)]
pub struct GraphEidCache<'a> {
    graph: &'a Graph,
    cache: Vec<(usize, usize)>,
}
impl<'a> std::ops::Index<usize> for GraphEidCache<'a> {
    type Output = (usize, usize);
    fn index(&self, index: usize) -> &Self::Output {
        &self.cache[index]
    }
}
#[derive(Clone, Debug)]
pub struct UnionFind {
    parents: Vec<isize>,
}
impl UnionFind {
    pub fn new(n: usize) -> Self {
        let parents = vec![-1; n];
        Self { parents }
    }
    pub fn find(&mut self, x: usize) -> usize {
        if self.parents[x] < 0 {
            x
        } else {
            let xx = self.parents[x] as usize;
            let y = self.find(xx);
            self.parents[x] = y as isize;
            y
        }
    }
    pub fn unite(&mut self, x: usize, y: usize) -> bool {
        use std::mem::swap;
        let mut x = self.find(x);
        let mut y = self.find(y);
        if x == y {
            return false;
        }
        if self.parents[x] > self.parents[y] {
            swap(&mut x, &mut y);
        }
        self.parents[x] += self.parents[y];
        self.parents[y] = x as isize;
        true
    }
    pub fn size(&mut self, x: usize) -> usize {
        let x = self.find(x);
        (-self.parents[x]) as usize
    }
    pub fn same(&mut self, x: usize, y: usize) -> bool {
        self.find(x) == self.find(y)
    }
    pub fn members(&mut self, x: usize) -> Vec<usize> {
        let root = self.find(x);
        (0..self.parents.len())
            .filter(|i| self.find(*i) == root)
            .collect::<Vec<usize>>()
    }
    pub fn roots(&mut self) -> Vec<usize> {
        (0..self.parents.len())
            .filter(|i| self.parents[*i] < 0)
            .collect::<Vec<usize>>()
    }
    pub fn all_group_members(&mut self) -> std::collections::HashMap<usize, Vec<usize>> {
        let mut groups_map = std::collections::HashMap::new();
        for x in 0..self.parents.len() {
            let r = self.find(x);
            groups_map.entry(r).or_insert(vec![]).push(x);
        }
        groups_map
    }
}
fn main() {
    #[allow(unused_imports)]
    use std::io::{Read as _, Write as _};
    let __out = std::io::stdout();
    let mut __in_buf = String::new();
    std::io::stdin().read_to_string(&mut __in_buf).unwrap();
    let mut scanner = Scanner::new(&__in_buf);
    #[allow(unused_macros)]
    macro_rules !scan {() =>{scan !(usize ) } ;(($($t :tt ) ,*) ) =>{($(scan !($t ) ) ,*) } ;([$t :tt ;$len :expr ] ) =>{(0 ..$len ) .map (|_ |scan !($t ) ) .collect ::<Vec <_ >>() } ;({chars :$b :expr } ) =>{scanner .scan_chars_with ($b ) } ;({$t :tt =>$f :expr } ) =>{$f (scan !($t ) ) } ;(chars ) =>{scanner .scan_chars () } ;($t :ty ) =>{scanner .scan ::<$t >() } ;}
    let mut __out = std::io::BufWriter::new(__out.lock());
    #[allow(unused_macros)]
    macro_rules !print {($($arg :tt ) *) =>(::std ::write !(__out ,$($arg ) *) .unwrap () ) }
    #[allow(unused_macros)]
    macro_rules !println {($($arg :tt ) *) =>(::std ::writeln !(__out ,$($arg ) *) .unwrap () ) }
    #[allow(unused_macros)]
    macro_rules! echo {
        ($iter :expr ) => {
            echo!($iter, "\n")
        };
        ($iter :expr ,$sep :expr ) => {
            let mut iter = $iter;
            if let Some(item) = iter.next() {
                print!("{}", item);
            }
            for item in iter {
                print!("{}{}", $sep, item);
            }
            println!();
        };
    }
    let n = scan!();
    let m = scan!();
    let ab = scan!([(marker::Usize1, marker::Usize1); m]);
    let mut uf = UnionFind::new(n);
    let mut g = Graph::new(n);
    let mut deg = vec![0; n];
    let mut ans = vec![];
    for &(a, b) in ab.iter() {
        if uf.unite(a, b) {
            g.add_undirected_edge(a, b);
        } else {
            ans.push((a, b));
            deg[a] += 1;
        }
    }
    let mut r = TreeRec::new(n, deg, ans);
    r.dfs(0, n, &g);
    if r.deg.iter().all(|&d| d % 2 == 0) {
        for (c, d) in r.ans {
            println!("{} {}", c + 1, d + 1);
        }
    } else {
        println!("-1");
    }
}
#[derive(Debug, Clone)]
pub struct TreeRec {
    pub n: usize,
    deg: Vec<usize>,
    ans: Vec<(usize, usize)>,
}
impl TreeRec {
    pub fn new(n: usize, deg: Vec<usize>, ans: Vec<(usize, usize)>) -> Self {
        Self { n, deg, ans }
    }
    pub fn dfs(&mut self, u: usize, p: usize, graph: &Graph) {
        for a in graph.adjacency(u).iter().filter(|a| a.to != p) {
            self.dfs(a.to, u, graph);
            let (x, y) = if self.deg[a.to] % 2 == 0 {
                (u, a.to)
            } else {
                (a.to, u)
            };
            self.ans.push((x, y));
            self.deg[x] += 1;
        }
    }
}

Measured memory_bytes: 23384