local mab = math.abs
local n, m = io.read("*n", "*n")
local pos, tm = 0, 0
local v = true
for i = 1, m do
  local t, p = io.read("*n", "*n")
  if t - tm < mab(p - pos) then
    v = false
  end
  pos, tm = p, t
end
print(v and "Yes" or "No")