/**
____ ____ ____ ____ ____ ____
||l |||e |||i |||n |||a |||d ||
||__|||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|/__\|
**/
#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
typedef long long ll;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
const int maxn = 210;
const ll inf = 1e18;
int n;
ll l, x[maxn], t[maxn], dp[maxn][maxn][maxn][2];
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];
x[n + 1] = l;
for (int i = 0; i <= n + 1; i ++)
for (int j = 0; j <= n + 1; j ++)
for (int f = 0; f <= n + 1; f ++)
dp[i][j][f][0] = dp[i][j][f][1] = inf;
dp[0][n + 1][0][0] = dp[0][n + 1][0][1] = 0;
ll ans = 0;
for (int f = 0; f <= n + 1; f ++)
{
for (int d = n; d > 0; d --)
{
for (int i = 0; i <= n - d + 1; i ++)
{
int j = i + d;
if (i != 0)
{
dp[i][j][f][0] = min(dp[i][j][f][0], dp[i - 1][j][f][0] + x[i] - x[i - 1]);
if (f > 0)
{
ll tp = dp[i - 1][j][f - 1][0] + x[i] - x[i - 1];
if (tp <= t[i])
dp[i][j][f][0] = min(dp[i][j][f][0], tp);
}
}
if (j != n + 1)
{
dp[i][j][f][1] = min(dp[i][j][f][1], dp[i][j + 1][f][1] + x[j + 1] - x[j]);
if (f > 0)
{
ll tp = dp[i][j + 1][f - 1][1] + x[j + 1] - x[j];
if (tp <= t[j])
{
dp[i][j][f][1] = min(dp[i][j][f][1], tp);
}
}
}
if (dp[i][j][f][0] + x[i] + l - x[j] < dp[i][j][f][1])
dp[i][j][f][1] = dp[i][j][f][0] + x[i] + l - x[j];
if (dp[i][j][f][1] + x[i] + l - x[j] < dp[i][j][f][0])
dp[i][j][f][0] = dp[i][j][f][1] + x[i] + l - x[j];
if (dp[i][j][f][0] != inf || dp[i][j][f][1] != inf)
ans = max(ans, (ll)f);
///cout << i << " " << j << " " << f << " " << dp[i][j][f][0] << " " << dp[i][j][f][1] << endl;
}
}
}
cout << ans << endl;
}
int main()
{
solve();
return 0;
}
