#include <bits/stdc++.h>
using namespace std;
#ifndef lisie_bimbi
#define endl '\n'
#pragma GCC optimize("O3")
#pragma GCC target("avx,avx2,bmi2,fma")
#endif
using ll = long long;
const ll inf = 1'000'000'000'000'000'000;
#define int long long
int n, l;
vector<int> x, t;
int dist(int a, int b){
if(b < a){
swap(a, b);
}
return min(b - a, l - (b - a));
}
void solve(){
cin >> n >> l;
x.resize(n);
t.resize(n);
for(int i = 0; i < n; i++){
cin >> x[i];
}
for(int i = 0; i < n; i++){
cin >> t[i];
}
vector<vector<vector<array<int, 2>>>> dp(n, vector<vector<array<int, 2>>>(n, vector<array<int, 2>>(n + 1, {inf, inf})));
for(int i = 0; i < n; i++){
dp[i][i][0] = {dist(0, x[i]), dist(0, x[i])};
if(dist(0, x[i]) <= t[i]){
dp[i][i][1] = {dist(0, x[i]), dist(0, x[i])};
}
}
for(int sz = 2; sz <= n; sz++){
for(int l = 0; l < n; l++){
int r = (l + sz - 1) % n;
for(int ans = 0; ans <= n; ans++){
dp[l][r][ans][0] = min(dp[l][r][ans][0], dp[(l + 1) % n][r][ans][0] + dist(x[l], x[(l + 1) % n]));
dp[l][r][ans][1] = min(dp[l][r][ans][1], dp[l][(r - 1 + n) % n][ans][1] + dist(x[(r - 1 + n) % n], x[r]));
if(ans > 0){
if(dp[(l + 1) % n][r][ans - 1][0] + dist(x[l], x[(l + 1) % n]) <= t[l]){
dp[l][r][ans][0] = min(dp[l][r][ans][0], dp[(l + 1) % n][r][ans - 1][0] + dist(x[l], x[(l + 1) % n]));
}
if(dp[l][(r - 1 + n) % n][ans - 1][1] + dist(x[(r - 1 + n) % n], x[r]) <= t[r]){
dp[l][r][ans][1] = min(dp[l][r][ans][1], dp[l][(r - 1 + n) % n][ans - 1][1] + dist(x[(r - 1 + n) % n], x[r]));
}
}
dp[l][r][ans][0] = min(dp[l][r][ans][0], dp[l][r][ans][1] + dist(x[l], x[r]));
dp[l][r][ans][0] = min(dp[l][r][ans][0], dp[l][r][ans][1] + dist(x[l], x[r]));
}
}
}
for(int ans = n; ans >= 0; ans--){
for(int l = 0; l < n; l++){
for(int r = 0; r < n; r++){
if((dp[l][r][ans][0] < inf) || (dp[l][r][ans][1] < inf)){
cout << ans << endl;
return;
}
}
}
}
}
signed main(){
#ifdef lisie_bimbi
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#else
#endif
cin.tie(nullptr)->sync_with_stdio(false);
int t = 1;
//cin >> t;
while(t--){
solve();
}
}
