#include<bits/stdc++.h>
using namespace std;
#define task "a"
#define se second
#define fi first
#define ll long long
#define ii pair<int, int>
const long mxN = 2e2 + 7, inf = 1e9 + 7;
int n, l, a[mxN];
ii t[mxN], dp[mxN][mxN][3];
bool Between(int u, int id, int v)
{
if (u <= v)
return (u <= id && id <= v);
else
return !(v < id && id < u);
}
int dis(int u, int v)
{
return (a[v] + l - a[u]) % l;
}
ii Plus(ii u, ii v)
{
u.fi += v.fi;
u.se -= v.se;
return u;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
//freopen(task".INP", "r", stdin);
//freopen(task".OUT", "w", stdout);
cin >> n >> l;
for (int i = 1; i <= n; i++)
cin >> a[i];
for (int i = 1; i <= n; i++)
{
cin >> t[i].fi;
t[i].se = i;
}
sort(t + 1, t + n + 1);
/*
dp[i][j][0/1] la time nho nhat
tai vi tri i
0 la trai
1 la phai
j la dau con lai
*/
// Reset dp
for (int i = 0; i <= n; i++)
{
for (int j = 0; j <= n; j++)
for (int dir = 0; dir <= 1; dir++)
dp[i][j][dir] = {inf, 0};
}
dp[0][0][0].fi = 0;
for (int i = 1; i <= n; i++)
{
for (int j = 0; j < i; j++)
{
for (int u = 0; u <= n; u++)
{
//dir = 0
if (!Between(u, t[i].se, t[j].se))
{
// nw dir = 0
dp[i][u][0] = min(dp[i][u][0], Plus(dp[j][u][0], {dis(t[j].se, t[i].se), 1}));
// nw dir = 1
dp[i][t[j].se][1] = min(dp[i][t[j].se][1], Plus(dp[j][u][0], {dis(t[i].se, t[j].se), 1}));
}
else
dp[j][u][0].se--;
// dir = 1
if (!Between(t[j].se, t[i].se, u))
{
// nw dir = 1
dp[i][u][1] = min(dp[i][u][1], Plus(dp[j][u][1], {dis(t[i].se, t[j].se), 1}));
// nw dir = 0
dp[i][t[j].se][0] = min(dp[i][t[j].se][0], Plus(dp[j][u][1], {dis(t[j].se, t[i].se), 1}));
}
else
dp[j][u][1].se--;
}
}
for (int j = 0; j <= n; j++)
{
for (int dir = 0; dir <= 1; dir++)
{
if (dp[i][j][dir].fi > t[i].fi)
dp[i][j][dir] = {inf, 0};
}
}
}
int ans = 0;
for (int i = 0; i <= n; i++)
{
for (int j = 0; j <= n; j++)
for (int dir = 0; dir <= 1; dir++)
{
if (dp[i][j][dir].fi != inf)
ans = max(-dp[i][j][dir].se, ans);
}
}
cout << ans;
}
