#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize ("Ofast")
#pragma GCC target("fma,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#pragma GCC optimize("unroll-loops")
const int N = 2e2 + 5;
long long dp [N][N][N][2];
int pos [N];
int lim [N];
/*
* DP[N][N][N][2]
* Minimum time possible for being at pos [i, j] - 0 / 1, with x elements so far
*/
int main () {
ios::sync_with_stdio(0);
cin.tie(0);
int n, tamanho;
cin >> n >> tamanho;
n += 2;
pos[0] = 0;
lim[0] = 1e9;
pos[n - 1] = 0;
lim[n - 1] = 1e9;
for (int i = 1; i < n - 1; i++) cin >> pos[i];
for (int i = 1; i < n - 1; i++) cin >> lim[i];
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
for (int x = 0; x < N; x++) {
dp[i][j][x][0] = dp[i][j][x][1] = 1e16;
}
}
}
dp[0][n - 1][0][0] = dp[0][n - 1][0][1] = 0;
for (int L = 0; L < n; L++) {
for (int R = n - 1; R >= 0; R--) {
for (int Q = 0; Q <= n; Q++) {
if (L + 1 < n && L + 1 < R) {
// ESQ -> ESQ
long long tempo = dp[L][R][Q][0] + pos[L + 1] - pos[L];
assert(tempo >= 0);
int QTS = Q + (tempo <= lim[L + 1]);
dp[L + 1][R][QTS][0] = min (dp[L + 1][R][QTS][0], tempo);
// DIR -> ESQ
tempo = dp[L][R][Q][1] + tamanho - pos[R] + pos[L + 1];
assert(tempo >= 0);
QTS = Q + (tempo <= lim[L + 1]);
dp[L + 1][R][QTS][0] = min (dp[L + 1][R][QTS][0], tempo);
}
if (R - 1 >= 0 && R - 1 > L) {
// DIR -> DIR
long long tempo = dp[L][R][Q][1] + abs (pos[R] - pos[R - 1]);
assert(tempo >= 0);
int QTS = Q + (tempo <= lim[R - 1]);
dp[L][R - 1][QTS][1] = min (dp[L][R - 1][QTS][1], tempo);
// ESQ -> DIR
tempo = dp[L][R][Q][0] + pos[L] + tamanho - pos[R - 1];
assert(tempo >= 0);
QTS = Q + (tempo <= lim[R - 1]);
dp[L][R - 1][QTS][1] = min (dp[L][R - 1][QTS][1], tempo);
}
}
}
}
int mx = 0;
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
for (int x = 0; x < N; x++) {
if (dp[i][j][x][0] < 1e15 || dp[i][j][x][1] < 1e15) {
// cout << i << ' ' << j << ' ' <<' ' << x << ' ' << dp[i][j][x][1] << '\n';
mx = max (mx, x);
}
}
}
}
cout << mx << '\n';
return 0;
}
