#include<bits/stdc++.h>
#define ll long long
const int nmax = 200 + 5, N = 3e5 + 5;
const ll oo = 1e18;
const int lg = 7, M = 4e3;
const int base = 2e5, mod = 998244353;
#define pii pair<ll, ll>
#define fi first
#define se second
#define endl "\n"
#define debug(a, n) for(int i = 1; i <= n; ++i) cout << a[i] << ' ';cout << endl
using namespace std;
int n, m, L;
int a[nmax * 2];
ll f[nmax][nmax * 2][nmax][2];
int b[nmax * 2];
void ckmin(ll &a, ll b){
a = min(a, b);
}
int cost(int i, int j, int x, int cur){
if(x > j){
x -= m;
return ((x >= i) == 0 && b[x] >= cur);
}
else{
x += m;
return ((x <= j) == 0 && b[x] >= cur);
}
return 0;
}
main(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
// freopen("code.inp", "r", stdin);
// freopen("code.out", "w", stdout);
cin >> n >> L;
memset(f, 0x3f, sizeof f);
for(int i = 1; i <= n; ++i) cin >> a[i];
for(int i = 1; i <= n; ++i) cin >> b[i];
a[++n] = L;
m = n - 1;
for(int i = 1; i <= m; ++i){
a[++n] = a[i];
b[n] = b[i];
}
++m;
f[m][m][0][0] = f[m][m][0][1] = 0;
// cout << cost(m, m, m - 1, 2) << ' ';
for(int i = m; i >= 1; --i){
for(int j = m; j <= n; ++j){
for(int k = 0; k <= m; ++k){
int res = a[m] - a[i];
if(j != m) res += a[j];
ckmin(f[i][j][k][0], f[i][j][k][1] + res);
ckmin(f[i][j][k][1], f[i][j][k][0] + res);
//
ll cur = f[i][j][k][0] + abs(a[i - 1] - a[i]);
ckmin(f[i - 1][j][k + cost(i, j, i - 1, cur)][0], cur);
cur = f[i][j][k][1];
if(j == m) cur += a[j + 1];
else cur += a[j + 1] - a[j];
ckmin(f[i][j + 1][k + cost(i, j, j + 1, cur)][1], cur);
}
}
}
// cout << f[5][m + 1][2][1] << ' ';
int ans = 0;
for(int k = m; k >= 0; --k){
for(int i = 1; i <= m; ++i){
for(int j = m; j <= n; ++j){
if(min(f[i][j][k][0], f[i][j][k][1]) < oo) cout << k, exit(0);
}
}
}
}
/*
4 5
3 1 3 7
3 2 0 4
1 2 5 1
4 2 4 9
3 4 3 9
*/
