#include <bits/stdc++.h>
using namespace std;
#define scd(t) scanf("%d", &t)
#define sclld(t) scanf("%lld", &t)
#define forr(i, j, k) for (int i = j; i < k; i++)
#define frange(i, j) forr(i, 0, j)
#define all(cont) cont.begin(), cont.end()
#define mp make_pair
#define pb push_back
#define f first
#define s second
typedef long long int lli;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<lli> vll;
typedef vector<string> vs;
typedef vector<pii> vii;
typedef vector<vi> vvi;
typedef map<int, int> mpii;
typedef set<int> seti;
typedef multiset<int> mseti;
typedef long double ld;
void usaco()
{
freopen("/media/hariaakash646/785EF1075EF0BF46/CompetitiveProgramming/input.in", "r", stdin);
// freopen("problem.out", "w", stdout);
}
int main() {
// usaco();
int n;
lli l;
scd(n);
sclld(l);
vector<lli> vec(n+1), tim(n+1);
frange(i, n) {
sclld(vec[i+1]);
}
frange(i, n) {
sclld(tim[i+1]);
}
tim[0] = -1;
vector<vector<vll>> dp1(n+1, vector<vll>(n+1, vll(n+1, 2e18+5))), dp2(n+1, vector<vll>(n+1, vll(n+1, 2e18+5)));
dp1[0][0][0] = dp2[0][0][0] = 0;
forr(le, 1, n+1) {
forr(j, 0, n+1) {
int k = (j + le) % (n+1);
int i = 0;
dp1[j][k][i] = min(dp1[(j+1)%(n+1)][k][i] + (vec[(j+1) % (n+1)] - vec[j] + l) % l, dp2[(j+1) % (n+1)][k][i] + (vec[k] + l - vec[j]) % l);
dp2[j][k][i] = min(dp1[j][(k-1+n+1)%(n+1)][i] + (l - vec[j] + vec[k]) % l, dp2[j][(k-1+n+1)%(n+1)][i] + (vec[k] + l - vec[(k-1+n+1)%(n+1)]));
}
}
forr(i, 1, n+1) {
forr(le, 1, n+1) {
forr(j, 0, n+1) {
int k = (j + le) % (n+1);
dp1[j][k][i] = min(dp1[(j+1)%(n+1)][k][i] + (vec[(j+1) % (n+1)] - vec[j] + l) % l, dp2[(j+1) % (n+1)][k][i] + (vec[k] + l - vec[j]) % l);
if(dp1[(j+1)%(n+1)][k][i-1] + (vec[(j+1) % (n+1)] - vec[j] + l) % l <= tim[j]) {
dp1[j][k][i] = min(dp1[j][k][i], dp1[(j+1)%(n+1)][k][i-1] + (vec[(j+1) % (n+1)] - vec[j] + l) % l);
}
if(dp2[(j+1) % (n+1)][k][i-1] + (vec[k] + l - vec[j]) % l <= tim[j]) {
dp1[j][k][i] = min(dp1[j][k][i], dp2[(j+1) % (n+1)][k][i-1] + (vec[k] + l - vec[j]) % l);
}
dp2[j][k][i] = min(dp1[j][(k-1+n+1)%(n+1)][i] + (l - vec[j] + vec[k]) % l, dp2[j][(k-1+n+1)%(n+1)][i] + (vec[k] + l - vec[(k-1+n+1)%(n+1)]) % l);
if(dp1[j][(k-1+n+1)%(n+1)][i-1] + (l - vec[j] + vec[k]) % l <= tim[k]) {
dp2[j][k][i] = min(dp2[j][k][i], dp1[j][(k-1+n+1)%(n+1)][i-1] + (l - vec[j] + vec[k]) % l);
}
if(dp2[j][(k-1+n+1)%(n+1)][i-1] + (vec[k] + l - vec[(k-1+n+1)%(n+1)]) % l <= tim[k]) {
dp2[j][k][i] = min(dp2[j][k][i], dp2[j][(k-1+n+1)%(n+1)][i-1] + (vec[k] + l - vec[(k-1+n+1)%(n+1)]) % l);
}
}
}
}
for(int v=n; v>= 0; v--) {
frange(i, n+1) {
frange(j, n+1) {
if(dp1[i][j][v] < 2e18+5 || dp2[i][j][v] < 2e18+5) {
printf("%d\n", v);
return 0;
}
}
}
}
}
