#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize ("trapv")
const int inf = 2e9;
int dp[203][203][203][2];
int n, l, a[203], t[203];
int ans (int x, int y, int z, int c) { //left, right, count, is it at right?
if (x == n + 1 && y == 0) {
if (z == 0) return 0;
return inf;
}
if (z < 0) return inf;
int &ret = dp[x][y][z][c];
if (ret != -1) return ret;
ret = inf;
if (c == 0) {
if (x != n + 1) {
if (y != 0) {
int cost = l - a[x] + a[y];
ret = min(ret, ans(x + 1, y, z, 1) + cost);
if (ans(x + 1, y, z - 1, 1) + cost <= t[x]) {
ret = min(ret, ans(x + 1, y, z - 1, 1) + cost);
}
}
if (x != n + 1) {
int cost = a[x + 1] - a[x];
ret = min(ret, ans(x + 1, y, z, 0) + cost);
if (ans(x + 1, y, z - 1, 0) + cost <= t[x]) {
ret = min(ret, ans(x + 1, y, z - 1, 0) + cost);
}
}
}
} else {
if (y != 0) {
if (x != n + 1) {
int cost = l - a[x] + a[y];
ret = min(ret, ans(x, y - 1, z, 0) + cost);
if (ans(x, y - 1, z - 1, 0) + cost <= t[y]) {
ret = min(ret, ans(x, y - 1, z - 1, 0) + cost);
}
}
if (y != 0) {
int cost = a[y] - a[y - 1];
ret = min(ret, ans(x, y - 1, z, 1) + cost);
if (ans(x, y - 1, z - 1, 1) + cost <= t[y]) {
ret = min(ret, ans(x, y - 1, z - 1, 1) + cost);
}
}
}
}
return ret;
}
void solve () {
cin >> n >> l;
a[0] = 0; a[n + 1] = l;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
for (int i = 1; i <= n; i++) {
cin >> t[i];
}
memset(dp, -1, sizeof(dp));
int ret = 0;
for (int i = 1; i <= n; i++) {
for (int j = 0; j <= n + 1; j++) {
for (int k = j + 1; k <= n + 1; k++) {
if (ans(k, j, i, 0) != inf || ans(k, j, i, 1) != inf) {
ret = i;
}
}
}
}
cout << ret << '\n';
}
signed main () {
ios::sync_with_stdio(0); cin.tie(0);
int tc = 1; //cin >> tc;
while (tc--) solve();
}
