#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
const int mxN = 205;
ll n,x[mxN],t[mxN],L,dp[mxN][mxN][mxN][2],inf = 1e17;
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
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 + 1; i++) for(int j = 0; j <= n + 1; j++) for(int k = 0; k <= n + 1; k++){
dp[i][j][k][0] = dp[i][j][k][1] = inf;
dp[0][j][k][0] = x[k];
dp[0][j][k][1] = L - x[j];
}
dp[0][0][0][0] = dp[0][0][0][1] = 0;
x[n + 1] = L;
ll ans = 0;
for(int k = 1; k <= n; k++){
for(ll i1 = n + 1; i1 >= 1; i1--){
ll i = i1 % (n + 1);
if(i1 != n + 1){
ll num = dp[k - 1][(i + 1) % (n + 1)][0][1];
dp[k][i][0][1] = min(num + ((t[i] >= num + x[i + 1] - x[i]) ? (x[i + 1] - x[i]) : inf), inf);
dp[k][i][0][1] = min(dp[k][i][0][1], dp[k][(i + 1) % (n + 1)][0][1] + x[i + 1] - x[i]);
dp[k][i][0][0] = min(dp[k][i][0][1] + L - x[i], dp[k][(i + 1) % (n + 1)][0][0]);
}
for(ll j = 1; j != i1; j++){
ll num = dp[k - 1][i][j - 1][0];
dp[k][i][j][0] = min(num + ((t[j] >= num + x[j] - x[j - 1]) ? (x[j] - x[j - 1]) : inf),inf);
dp[k][i][j][0] = min(dp[k][i][j][0], dp[k][i][j - 1][0] + x[j] - x[j - 1]);
if(i1 != n + 1){
dp[k][i][j][0] = min(dp[k][i][j][0], dp[k][(i + 1) % (n + 1)][j][0]);
}
else{
dp[k][0][j][1] = min(dp[k][0][j - 1][1], dp[k][0][j][0] + x[j]);
continue;
}
num = dp[k - 1][(i + 1) % (n + 1)][j][1];
dp[k][i][j][1] = min(min(num + ((t[i] >= num + x[i + 1] - x[i]) ? (x[i + 1] - x[i]) : inf),
dp[k][i][j - 1][1]), inf);
dp[k][i][j][1] = min(dp[k][i][j][1], dp[k][(i + 1) % (n + 1)][j][1] + x[i + 1] - x[i]);
dp[k][i][j][0] = min(dp[k][i][j][0], dp[k][i][j][1] + L - x[i] + x[j]);
dp[k][i][j][1] = min(dp[k][i][j][1], dp[k][i][j][0] + L - x[i] + x[j]);
}
}
}
//5 20
//1 2 17 18 19
//1 8 5 4 3
for(int i = 0; i <= n; i++) for(int j = 0; j <= n; j++) for(int k = 0; k <= n; k++){
if(dp[i][j][k][0] < inf or dp[i][j][k][1] < inf) ans = max(ans, (ll)i);
}
cout << ans;
}
