#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e2+10;
typedef long long ll;
const ll inf = 1e18;
ll dp[maxn][maxn][maxn][2], x[maxn], t[maxn];
int main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
ll n, l;
cin >> n >> l;
for(int i=1; i<=n; i++) cin >> x[i];
for(int i=1; i<=n; i++) cin >> t[i];
for(int i=0; i<=n; i++){
for(int j=0; j<=n; j++){
for(int k=0; k<=n; k++){
dp[i][j][k][0] = dp[i][j][k][1] = inf;
}
}
}
dp[0][0][0][0] = dp[0][0][0][1] = 0;
auto prv = [&](ll x){
if(x-1 < 1) return n;
return x-1;
};
auto nxt = [&](ll x){
if(x+1 > n) return 1LL;
return x+1;
};
auto d = [&](ll a, ll b){
if(a > b) swap(a, b);
return min(x[b] - x[a], l - x[b] + x[a]);
};
auto min_self = [&](ll &a, ll &b){
a = min(a, b);
};
for(ll len=0; len<n; len++){
for(ll i=0; i<=n; i++){
for(ll k=0; k<=len; k++){
ll j = (i + len)%(n+1);
//l -> l
ll tt = dp[i][j][k][0] + d(prv(i), i);
min_self(dp[prv(i)][j][k+(tt <= t[prv(i)])][0], tt);
//r -> l
tt = dp[i][j][k][1] + d(prv(i), j);
min_self(dp[prv(i)][j][k+(tt <= t[prv(i)])][0], tt);
//l -> r
tt = dp[i][j][k][0] + d(i, nxt(j));
min_self(dp[i][nxt(j)][k+(tt <= t[nxt(j)])][1], tt);
//r -> r
tt = dp[i][j][k][1] + d(j, nxt(j));
min_self(dp[i][nxt(j)][k+(tt <= t[nxt(j)])][1], tt);
}
}
}
ll ans = 0;
for(ll i=0; i<=n; i++){
for(ll j=0; j<=n; j++){
for(ll k=0; k<=n; k++){
for(int q : {0, 1}){
if(dp[i][j][k][q] != inf) ans = max(ans, k);
}
}
}
}
cout << ans << "\n";
return 0;
}
