local mfl, mce = math.floor, math.ceil
local mmi, mma = math.min, math.max
local bls, brs = bit.lshift, bit.rshift
local SegTree = {}
SegTree.updateAll = function(self)
  for i = self.stagenum - 1, 1, -1 do
    local cnt = bls(1, i - 1)
    for j = 1, cnt do
      self.stage[i][j] = self.func(self.stage[i + 1][j * 2 - 1], self.stage[i + 1][j * 2])
    end
  end
end
SegTree.create = function(self, n, func, emptyvalue)
  self.func, self.emptyvalue = func, emptyvalue
  local stagenum, mul = 1, 1
  self.stage = {{}}
  while mul < n do
    mul, stagenum = mul * 2, stagenum + 1
    self.stage[stagenum] = {}
  end
  self.stagenum = stagenum
  self.left_stage = {}
  for i = 1, n do
    local sp, sz = 1, bls(1, stagenum - 1)
    while(i - 1) % sz ~= 0 do
      sp, sz = sp + 1, brs(sz, 1)
    end
    self.left_stage[i] = sp
  end
  self.sz_stage = {}
  local tmp, sp = 1, stagenum
  for i = 1, n do
    if tmp * 2 == i then tmp, sp = tmp * 2, sp - 1 end
    self.sz_stage[i] = sp
  end
  for i = 1, n do self.stage[stagenum][i] = i end
  for i = n + 1, mul do self.stage[stagenum][i] = emptyvalue end
  self:updateAll()
end
SegTree.getRange = function(self, left, right)
  if left == right then return self.stage[self.stagenum][left] end
  local stagenum = self.stagenum
  local ret = self.emptyvalue
  while left <= right do
    local stage = mma(self.left_stage[left], self.sz_stage[right - left + 1])
    local sz = bls(1, stagenum - stage)
    ret = self.func(ret, self.stage[stage][1 + brs(left - 1, stagenum - stage)])
    left = left + sz
  end
  return ret
end
SegTree.update = function(self, idx, value)
  for i = self.stagenum - 1, 1, -1 do
    local dst = brs(idx + 1, 1)
    local rem = dst * 4 - 1 - idx
    self.stage[i][dst] = self.func(self.stage[i + 1][idx], self.stage[i + 1][rem])
    idx = dst
  end
end
SegTree.new = function(n, func, emptyvalue)
  local obj = {}
  setmetatable(obj, {__index = SegTree})
  obj:create(n, func, emptyvalue)
  return obj
end

local n, m = io.read("*n", "*n")
local edge = {}
local edgenum = {}
local offset = {}
for i = 1, n do
  edge[i] = {}
  edgenum[i] = 0
  offset[i] = 0
end
local inf = 1000000007
edgenum[n + 1] = inf
for i = 1, m do
  local a, b = io.read("*n", "*n")
  edge[a][b], edge[b][a] = true, true
  edgenum[a] = edgenum[a] + 1
  edgenum[b] = edgenum[b] + 1
end
if m % 2 == 1 then
  print(-1)
  os.exit()
end
local st = SegTree.new(n, function(a, b) return edgenum[a] < edgenum[b] and a or b end, n + 1)
for i = 1, n do
  local src = st.stage[1][1]
  local dsts = {}
  for dst, _u in pairs(edge[src]) do
    table.insert(dsts, dst)
  end
  if offset[src] == 1 then
    local dst = dsts[#dsts]
    print(src .. " " .. dst)
    edgenum[dst] = edgenum[dst] - 1
    edge[dst][src] = nil
    st:update(dst)
    table.remove(dsts)
  end
  local lim = mfl(#dsts / 2)
  for j = 1, lim * 2 do
    local dst = dsts[j]
    print(src .. " " .. dst)
    edge[dst][src] = nil
    edgenum[dst] = edgenum[dst] - 1
    st:update(dst)
  end
  if #dsts % 2 == 1 then
    local dst = dsts[#dsts]
    print(dst .. " " .. src)
    offset[dst] = (offset[dst] + 1) % 2
    edge[dst][src] = nil
    edgenum[dst] = edgenum[dst] - 1
    st:update(dst)
  end
  edgenum[src] = inf
  st:update(src)
end


Measured memory_bytes: 34620