#include <bits/stdc++.h>
// #include <ext/rope>
// #include <ext/pb_ds/assoc_container.hpp>
// using namespace __gnu_pbds;
// using namespace __gnu_cxx;
using namespace std;
// #define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ll long long
#define ull unsigned long long
#define ld long double
#define pb push_back
#define bit(mask, i) ((mask >> i) & 1)
#define el '\n'
#define F first
#define S second
template <class X, class Y> bool maximize(X &x, const Y &y) { return (x < y ? x = y, 1 : 0); }
template <class X, class Y> bool minimize(X &x, const Y &y) { return (x > y ? x = y, 1 : 0); }
const int INF = 1e9;
const ll LINF = 1e18;
const int MOD = 1e9 + 7;
const int MULTI = 0;
const ld eps = 1e-9;
const int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0}; // R D L U
const int ddx[4] = {-1, 1, 1, -1}, ddy[4] = {1, 1, -1, -1}; // UR DR DL UL
const char cx[4] = {'R', 'D', 'L', 'U'};
const ll base = 31;
const int nMOD = 2;
const ll mods[] = {(ll)1e9 + 10777, (ll)1e9 + 19777, (ll)1e9 + 3, (ll)1e9 + 3777};
const int N = 2e2 + 5;
int n, l, x[N], t[N];
ll dp[N][N][N][2];
int DIST(int i, int j) {
if (i == n + 1) return min(x[j], l - x[j]);
if (j == n + 1) return min(x[i], l - x[i]);
if (i > j) swap(i, j);
return min(x[j] - x[i], l - x[j] + x[i]);
}
void solve() {
cin >> n >> l;
for (int i = 1; i <= n; ++i)
cin >> x[i];
for (int i = 1; i <= n; ++i)
cin >> t[i];
memset(dp, 0x3f, sizeof(dp));
dp[n + 1][n + 1][0][0] = dp[n + 1][n + 1][0][1] = 0;
for (int len = 1; len <= n; ++len)
for (int i = 1; i <= n + 1; ++i)
for (int score = 0; score <= n; ++score) {
int j;
if (i == n + 1)
j = (len == 1 ? n + 1 : len - 1);
else if (i + len - 1 <= n + 1)
j = i + len - 1;
else
j = i + len - n - 2;
int prv = (i == 1 ? n + 1 : i - 1);
int nxt = (j == n + 1 ? 1 : j + 1);
if (dp[i][j][score][0] < LINF) {
int dist = DIST(i, prv);
int add = (dp[i][j][score][0] + dist <= t[prv]);
minimize(dp[prv][j][score + add][0], dp[i][j][score][0] + dist);
dist = DIST(i, nxt);
add = (dp[i][j][score][0] + dist <= t[nxt]);
minimize(dp[i][nxt][score + add][1], dp[i][j][score][0] + dist);
}
if (dp[i][j][score][1] < LINF) {
int dist = DIST(j, nxt);
int add = (dp[i][j][score][1] + dist <= t[nxt]);
minimize(dp[i][nxt][score + add][1], dp[i][j][score][1] + dist);
dist = DIST(j, prv);
add = (dp[i][j][score][1] + dist <= t[prv]);
minimize(dp[prv][j][score + add][0], dp[i][j][score][1] + dist);
}
}
int res = 0;
for (int i = 1; i <= n + 1; ++i)
for (int j = 1; j <= n + 1; ++j)
for (int score = 0; score <= n; ++score)
for (int t = 0; t < 2; ++t)
if (dp[i][j][score][t] < LINF)
maximize(res, score);
cout << res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (!MULTI) solve();
else {
int test; cin >> test;
while (test--) solve();
}
return 0;
}
