#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
const long long INF = 1e18;
// DP holati: dp[i][j][k][pos]
// i - soat mili bo'yicha olingan shtamplar soni (o'ngga)
// j - soat miliga qarshi olingan shtamplar soni (chapga)
// k - jami to'plangan shtamplar soni
// pos - hozirgi turgan joy (0: o'ng tomondagi oxirgi nuqtada, 1: chap tomondagi oxirgi nuqtada)
long long dp[205][205][205][2];
int main() {
int N;
long long L;
cin >> N >> L;
vector<long long> X(N + 2), T(N + 2);
for (int i = 1; i <= N; i++) cin >> X[i];
for (int i = 1; i <= N; i++) cin >> T[i];
// Chegaraviy qiymatlarni o'rnatamiz (0 - boshlang'ich nuqta)
X[0] = 0; X[N + 1] = L;
// DPni cheksizlik bilan to'ldiramiz
for (int i = 0; i <= N; i++)
for (int j = 0; i + j <= N; j++)
for (int k = 0; k <= N; k++)
dp[i][j][k][0] = dp[i][j][k][1] = INF;
dp[0][0][0][0] = dp[0][0][0][1] = 0;
for (int i = 0; i <= N; i++) {
for (int j = 0; i + j <= N; j++) {
for (int k = 0; k <= i + j; k++) {
if (dp[i][j][k][0] == INF && dp[i][j][k][1] == INF) continue;
// Hozirgi koordinatalar
long long curX_R = X[i];
long long curX_L = (j == 0) ? 0 : X[N - j + 1];
// 1. O'ngdan o'ngga o'tish (i -> i+1)
if (i + j < N) {
long long nextX = X[i + 1];
// Holat 0 dan (o'ngdan) o'ngga
long long time0 = dp[i][j][k][0] + (nextX - curX_R);
int nextK = k + (time0 <= T[i + 1] ? 1 : 0);
dp[i + 1][j][nextK][0] = min(dp[i + 1][j][nextK][0], time0);
// Holat 1 dan (chapdan) o'ngga
long long time1 = dp[i][j][k][1] + (curX_L == 0 ? nextX : (L - curX_L + nextX));
nextK = k + (time1 <= T[i + 1] ? 1 : 0);
dp[i + 1][j][nextK][0] = min(dp[i + 1][j][nextK][0], time1);
}
// 2. Chapga o'tish (j -> j+1)
if (i + j < N) {
long long nextX = X[N - j];
// Holat 0 dan (o'ngdan) chapga
long long time0 = dp[i][j][k][0] + (curX_R == 0 ? (L - nextX) : (curX_R + L - nextX));
int nextK = k + (time0 <= T[N - j] ? 1 : 0);
dp[i][j + 1][nextK][1] = min(dp[i][j + 1][nextK][1], time0);
// Holat 1 dan (chapdan) chapga
long long time1 = dp[i][j][k][1] + (curX_L - nextX);
if (j == 0) time1 = L - nextX; // Boshlang'ich holatdan chapga
nextK = k + (time1 <= T[N - j] ? 1 : 0);
dp[i][j + 1][nextK][1] = min(dp[i][j + 1][nextK][1], time1);
}
}
}
}
// Maksimal k ni topamiz
int ans = 0;
for (int i = 0; i <= N; i++)
for (int j = 0; i + j <= N; j++)
for (int k = 0; k <= N; k++)
if (dp[i][j][k][0] != INF || dp[i][j][k][1] != INF)
ans = max(ans, k);
cout << ans << endl;
return 0;
}
