function Main(input) {
    const [[N, H], ...AB] = input.split("\n").map(e => e.split(" ").map(Number));
    let sum = new Array(H + 1).fill(0);
    for (let i = 0; i < N; i++) {
        const [A, B] = AB[i];
        sum[A]++;
        sum[B + 1]--; 
    }
    let now = 0;
    let max = 0;
    for (let i = 0; i <= H; i++) {
        now += sum[i];
        max = Math.max(now, max);
    }
    console.log(max);
}
Main(require("fs").readFileSync(0)+"")