#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N = 205;
ll n, l;
ll cl[N], ccl[N], t[N];
void read() {
cin >> n >> l;
for(int i = 1; i <= n; i++) {
cin >> cl[i];
ccl[i] = l - cl[i];
}
for(int i = 1; i <= n; i++)
cin >> t[i];
}
struct state {
int l, r, cnt, dir;
state(int _l, int _r, int _cnt, int _dir) : l(_l), r(_r), cnt(_cnt), dir(_dir) {}
bool operator<(const state& ot) const {
return cnt < ot.cnt;
}
};
void solve() {
priority_queue<pair<ll, state>, vector<pair<ll, state>>, greater<pair<ll, state>>> pq;
ll dist[n+2][n+2][n+2][2];
for(int i = 1; i <= n+1; i++) {
for(int j = i-1; j <= n; j++) {
for(int k = 0; k <= n; k++)
dist[i][j][k][0] = dist[i][j][k][1] = -1;
}
}
ll cost, total;
int ans = 0;
pq.emplace(0, state(1, n, 0, 0));
dist[1][n][0][0] = 0;
while(!pq.empty()) {
ll d = pq.top().first; state u = pq.top().second; pq.pop();
if(dist[u.l][u.r][u.cnt][u.dir] == d) {
if(u.l > u.r) {
ans = max(ans, u.cnt);
continue;
}
if(u.dir == 0) {
cost = ((u.l==1)?0:-cl[u.l-1]) + cl[u.l];
total = d + cost;
ll& nxt1 = dist[u.l+1][u.r][u.cnt + (total <= t[u.l])][0];
if(nxt1 == -1 || nxt1 > total) {
nxt1 = total;
pq.emplace(nxt1, state(u.l+1, u.r, u.cnt + (total <= t[u.l]), 0));
}
cost = ((u.l==1)?0:cl[u.l-1]) + ccl[u.r];
total = d + cost;
ll& nxt2 = dist[u.l][u.r-1][u.cnt + (total <= t[u.r])][1];
if(nxt2 == -1 || nxt2 > total) {
nxt2 = total;
pq.emplace(nxt2, state(u.l, u.r-1, u.cnt + (total <= t[u.r]), 1));
}
} else {
cost = ((u.r==n)?0:-ccl[u.r+1]) + ccl[u.r];
total = d + cost;
ll& nxt1 = dist[u.l][u.r-1][u.cnt + (total <= t[u.r])][1];
if(nxt1 == -1 || nxt1 > total) {
nxt1 = total;
pq.emplace(nxt1, state(u.l, u.r-1, u.cnt + (total <= t[u.r]), 1));
}
cost = ((u.r==n)?0:ccl[u.r+1]) + cl[u.l];
total = d + cost;
ll& nxt2 = dist[u.l+1][u.r][u.cnt + (total <= t[u.l])][0];
if(nxt2 == -1 || nxt2 > total) {
nxt2 = total;
pq.emplace(nxt2, state(u.l+1, u.r, u.cnt + (total <= t[u.l]), 0));
}
}
}
}
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
read();
solve();
return 0;
}
