import std.algorithm, std.conv, std.range, std.stdio, std.string;

void main()
{
  auto rd1 = readln.split.to!(int[]), n = rd1[0], m = rd1[1];
  auto d = new int[](n);
  foreach (_; 0..m) {
    auto rd2 = readln.split.to!(int[]), a = rd2[0], b = rd2[1];
    ++d[a];
    ++d[b];
  }
  auto b = d.count!"a % 2 == 1";
  writeln(b == 0 || b == 2 ? "YES" : "NO");
}