#include <bits/stdc++.h>
using namespace std;
#define task "main"
#define no "NO"
#define yes "YES"
#define F first
#define S second
#define vec vector
#define _mp make_pair
#define ii pair<int, int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define evoid(val) return void(std::cout << val)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FOD(i, b, a) for(int i = (b); i >= (a); --i)
const int MAX_N = (int)2e2 + 4;
const int INF = (int)1e9 + 1408;
int n, l;
int pos[MAX_N], timeLimit[MAX_N];
namespace sub2 {
ii dp[1 << 12][14];
int dist(int x, int y) {
if (x > y) swap(x, y);
return min(y - x, x + l - y);
}
void solve() {
FOR(mask, 1, (1 << n) - 1) {
FOR(i, 0, n - 1) {
dp[mask][i] = {INF, 0};
if (!((mask >> i) & 1)) continue;
if (__builtin_popcount(mask) == 1) {
dp[mask][i].F = dist(0, pos[i + 1]);
if (dp[mask][i].F <= timeLimit[i + 1]) dp[mask][i].S = 1;
continue;
}
int preMask = (mask ^ (1 << i));
FOR(last, 0, n - 1) {
if (!((preMask >> last) & 1)) continue;
int tmp = dp[preMask][last].F + dist(pos[last + 1], pos[i + 1]);
if (tmp < dp[mask][i].F) dp[mask][i] = {tmp, dp[preMask][last].S + (tmp <= timeLimit[i + 1])};
else if (tmp == dp[mask][i].F) dp[mask][i].S = max(dp[mask][i].S, dp[preMask][last].S + (tmp <= timeLimit[i + 1]));
}
}
}
int ans = 0;
FOR(mask, 1, (1 << n) - 1) FOR(i, 0, n - 1) ans = max(ans, dp[mask][i].S);
cout << ans << "\n";
}
}
void solve() {
cin >> n >> l;
FOR(i, 1, n) cin >> pos[i];
FOR(i, 1, n) cin >> timeLimit[i];
if (n <= 15) sub2::solve();
}
int32_t main() {
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
bool multitest = 0;
int numTest = 1;
if (multitest) cin >> numTest;
while (numTest--) {
solve();
}
return 0;
}
/* Lak lu theo dieu nhac!!!! */
