#include <bits/stdc++.h>
using namespace std;
template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}
#define REP(i, s, e) for (int i = s; i < e; i++)
#define RREP(i, s, e) for (int i = s; i >= e; i--)
typedef long long ll;
typedef long double ld;
#define MP make_pair
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
#define MT make_tuple
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
#ifdef DEBUG
#define debug(args...) _debug(args)
void _debug(const char* format, ...) {
va_list args;
va_start(args, format);
vprintf(format, args);
va_end(args);
}
#else
#define debug(args...)
#endif
#define INF 2000000005
#define LINF 1000000000000000005
#define MOD 1000000007
#define MAXN 205
int n, l;
ll x[MAXN], t[MAXN];
ll dp[MAXN][MAXN][5][MAXN];
int ans;
int main() {
scanf("%d%d", &n, &l);
REP (i, 1, n + 1) {
scanf("%lld", &x[i]);
}
REP (i, 1, n + 1) {
scanf("%lld", &t[i]);
}
x[0] = 0;
t[0] = -1;
n++;
REP (i, 0, n + 3) {
REP (j, 0, n + 3) {
REP (m, 0, 2) {
REP (k, 0, n + 3) {
dp[i][j][m][k] = LINF;
}
}
}
}
dp[0][0][0][0] = dp[0][0][1][0] = 0;
// dp[i][j][m][k] is with range from s to e and currently at s,
// minimum time to take k stamps
// i is the length, j is starting point, m is positive or negative
REP (i, 1, n) {
REP (j, 0, n) {
REP (m, 0, 2) {
int p = m ? 1 : -1;
int s = j, e = (j + i * p + n) % n;
REP (k, 0, n) {
int pk = k;
ll pc = min(abs(x[s] - x[(s + p + n) % n]),
min(abs(x[s] - x[(s + p + n) % n] - l),
abs(x[s] - x[(s + p + n) % n] + l)));
debug(" %lld %lld\n", x[s] - x[(s + p + n) % n], pc);
if (k != 0 && dp[i - 1][(j + p + n) % n][m][k - 1] + pc <= t[s]) {
pk--;
}
mnto(dp[i][j][m][k], dp[i - 1][(j + p + n) % n][m][pk] + pc);
int ppk = k;
ll ppc = min(abs(x[e] - x[s]),
min(abs(x[e] - x[s] - l),
abs(x[e] - x[s] + l)));
debug(" %lld %lld\n", x[e] - x[s], ppc);
if (k != 0 && dp[i - 1][e][!m][k - 1] + ppc <= t[s]) {
ppk--;
}
mnto(dp[i][j][m][k], dp[i - 1][e][!m][ppk] + ppc);
debug("%d %d %d %d: %lld\n", s, e, p, k, dp[i][j][m][k]);
if (dp[i][j][m][k] < LINF) {
mxto(ans, k);
}
}
}
}
}
printf("%d\n", ans);
return 0;
}
