#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = (ll)1e18;
int N;
ll Lt;
vector<ll> x, t;
// memo[l][r][k][side] = best (minimum) time we've seen so far to reach state (l,r,k,side)
static ll memo[205][205][205][2];
int best_count = 0;
// compute the circular distance on [0, Lt)
inline ll dist(ll A, ll B) {
ll d = llabs(A - B);
return min(d, Lt - d);
}
// dfs from state (l, r, k, side), with elapsed time = cur_t and stamps collected = k
// side = 0 means currently at x[l], side = 1 means at x[r]
void dfs(int l, int r, int k, int side, ll cur_t) {
// update global best
best_count = max(best_count, k);
// try to extend interval on the left (i.e. visit l+1)
if (l + 1 < r) {
ll next_pos = x[l+1];
ll here = (side == 0 ? x[l] : x[r]);
ll travel = dist(here, next_pos);
ll nt = cur_t + travel;
int nk = k + (nt <= t[l+1] ? 1 : 0);
int nside = 0; // now we're at the left end
int nl = l+1, nr = r;
if (nt < memo[nl][nr][nk][nside]) {
memo[nl][nr][nk][nside] = nt;
dfs(nl, nr, nk, nside, nt);
}
}
// try to extend interval on the right (i.e. visit r-1)
if (l < r - 1) {
ll next_pos = x[r-1];
ll here = (side == 0 ? x[l] : x[r]);
ll travel = dist(here, next_pos);
ll nt = cur_t + travel;
int nk = k + (nt <= t[r-1] ? 1 : 0);
int nside = 1; // now we're at the right end
int nl = l, nr = r-1;
if (nt < memo[nl][nr][nk][nside]) {
memo[nl][nr][nk][nside] = nt;
dfs(nl, nr, nk, nside, nt);
}
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> N >> Lt;
x.resize(N+2);
t.resize(N+2);
for(int i = 1; i <= N; ++i) cin >> x[i];
// add the “sentinel” stands at 0 and Lt
x[0] = 0;
x[N+1] = Lt;
t[0] = t[N+1] = -INF; // unreachable, but we never stamp them
for(int i = 1; i <= N; ++i) cin >> t[i];
// initialize memo to INF
for(int i = 0; i < 205; ++i)
for(int j = 0; j < 205; ++j)
for(int k = 0; k < 205; ++k)
memo[i][j][k][0] = memo[i][j][k][1] = INF;
// start from the “empty” interval [0, N+1], with 0 stamps, at both ends
memo[0][N+1][0][0] = memo[0][N+1][0][1] = 0;
dfs(0, N+1, 0, 0, 0);
dfs(0, N+1, 0, 1, 0);
cout << best_count << "\n";
return 0;
}
