#include<bits/stdc++.h>
using namespace std;
#define ll long long
const bool Multitest = 0;
const int N = 205;
void minimize(ll& a, ll b)
{
a = min(a, b);
}
int x[N], t[N]; int n, k;
ll dp[N][N][N], dis[N][N];
bool check(int l, int r, bool check, int val)
{
if(check == 1)
{
return t[r] >= val + dis[min(l, r)][max(l, r)];
}
return t[r] >= val + dis[max(l, r)][min(l, r)];
}
void work()
{
cin >> n >> k;
for(int i = 1 ; i <= n ; i++) cin >> x[i];
for(int i = 1 ; i <= n ; i++) cin >> t[i];
x[n + 1] = k;
for(int i = 0 ; i <= n + 1 ; i++)
{
for(int j = 0 ; j <= n + 1 ; j++)
{
if(i == j) continue;
if(i < j) dis[i][j] = x[j] - x[i];
else
{
dis[i][j] = k - (x[i] - x[j]);
}
}
}
for(int i = 0 ; i <= n + 1 ; i++)
{
for(int j = 0 ; j <= n + 1 ; j++)
{
for(int cnt = 0 ; cnt <= n + 1 ; cnt++)
{
dp[i][j][cnt] = 1e9 + 10;
}
}
}
dp[0][n + 1][0] = 0;
dp[n + 1][0][0] = 0;
int ans = 0;
for(int len = n + 2 ; len >= 1 ; len--)
{
for(int l = 0 ; l + len - 1 <= n + 1 ; l++)
{
int r = l + len - 1;
for(int cnt = 0 ; cnt <= l + (n + 1) - r ; cnt++)
{
// cout << l << ' ' << r << ' ' << cnt << ' ' << dp[l][r][cnt] << ' ' << t[l] << ' ' << ans << '\n';
// cout << l << ' ' << r << ' ' << cnt << ' ' << dp[r][l][cnt] << ' ' << t[r] << ' ' << ans << '\n';
if(ans < cnt && dp[l][r][cnt] <= t[l]) ans = cnt;
if(ans < cnt && dp[r][l][cnt] <= t[r]) ans = cnt;
for(int x = l ; x <= r ; x++)
{
if(check(r, x, 1, dp[r][l][cnt]) && x != r) minimize(dp[x][l][cnt + 1], dp[r][l][cnt] + dis[x][r]);
if(check(r, x, 0, dp[r][l][cnt]) && x != r) minimize(dp[x][r][cnt + 1], dp[r][l][cnt] + dis[r][x]);
if(check(l, x, 1, dp[l][r][cnt]) && x != l) minimize(dp[x][r][cnt + 1], dp[l][r][cnt] + dis[l][x]);
if(check(r, x, 0, dp[l][r][cnt]) && x != l) minimize(dp[x][l][cnt + 1], dp[l][r][cnt] + dis[x][l]);
}
}
}
}
// cout << dp[n - 4][0][5] << '\n';
cout << ans;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int q = 1;
if(Multitest) cin >> q;
while(q--) work();
}
