function Main(input) {
  input = input.split("\n").map((line) => line.trim());
  const [N, H] = input[0].split(" ").map(Number);
  const [A, B] = [[], []];
  for (let i = 0; i < N; i++) [A[i], B[i]] = input[i + 1].split(" ").map(Number);
  const imos = Array(H + 1).fill(0);
  for (let i = 0; i < N; i++) {
    const [a, b] = [A[i], B[i]];
    imos[a] += 1;
    imos[b + 1] -= 1;
  }
  for (let i = 1; i < H; i++) imos[i] += imos[i - 1];
  let max = 0;
  for (let i = 0; i < H; i++) max = Math.max(max, imos[i]);
  console.log(max);
}

Main(require("fs").readFileSync(0, "utf8"));