#include<bits/stdc++.h>
using namespace std;
const int N = 200;
const int inf = 1e9 + 10;
int v[N + 2];
int v2[N + 2];
int dp[N + 3][N + 3][N + 3][2];
int main(){
int n,nr;
int ans = 0;
cin>>n>>nr;
v[0] = 0;
v2[0] = 100;
for(int i = 1;i <= n;i++){
cin>>v[i];
}
for(int i = 1;i <= n;i++){
cin>>v2[i];
}
v[n + 1] = nr;
v2[n + 1] = 100;
n+=2;
for(int i = 0;i <= n;i++){
for(int j = 0;j <= i;j++){
for(int k = 0;k <= i;k++){
for(int p = 0;p <= 1;p++){
if(i == 0 && j == 0 && k == 0 && p == 0){
dp[i][j][k][p] = 0;
}else{
dp[i][j][k][p] = inf;
int leftid = n - 1 - (i - j);
int rightid = j;
int dist = v[rightid] + (nr - v[leftid]);
if(i == 0 || leftid <= rightid)continue;
if(p == 0){
if(leftid == n - 1)continue;
///to leftside
///from rightside
if(k != 0 && dist + dp[i - 1][j][k - 1][1] <= v2[leftid]){
dp[i][j][k][p] = min(dp[i][j][k][p],dist + dp[i - 1][j][k - 1][1]);
}else{
if(i != k)dp[i][j][k][p] = min(dp[i][j][k][p],dist + dp[i - 1][j][k][1]);
}
///from leftside
if(k != 0 && dp[i - 1][j][k - 1][0] + v[leftid + 1] - v[leftid] <= v2[leftid]){
dp[i][j][k][p] = min(dp[i][j][k][p],dp[i - 1][j][k - 1][0] + v[leftid + 1] - v[leftid]);
}else{
if(i != k)dp[i][j][k][p] = min(dp[i][j][k][p],dp[i - 1][j][k][0] + v[leftid + 1] - v[leftid]);
}
}else{
if(j == 0 || rightid == n)continue;
///to rightside
///from leftside
if(k != 0 && dist + dp[i - 1][j - 1][k - 1][0] <= v2[rightid]){
dp[i][j][k][p] = min(dp[i][j][k][p],dist + dp[i - 1][j - 1][k - 1][0]);
}else{
if(i != k)dp[i][j][k][p] = min(dp[i][j][k][p],dist + dp[i - 1][j - 1][k][0]);
}
///from rightside
if(k != 0 && (v[rightid] - v[rightid - 1]) + dp[i - 1][j - 1][k - 1][1] <= v2[rightid]){
dp[i][j][k][p] = min(dp[i][j][k][p],(v[rightid] - v[rightid - 1]) + dp[i - 1][j - 1][k - 1][1]);
}else{
if(i != k)dp[i][j][k][p] = min(dp[i][j][k][p],(v[rightid] - v[rightid - 1]) + dp[i - 1][j - 1][k][1]);
}
}
if(dp[i][j][k][p] != inf){
ans = max(ans,k);
}
//cout<<dp[i][j][k][p]<<' '<<i<<' '<<j<<' '<<k<<' '<<p<<' '<<dist<<' '<<leftid<<' '<<v[leftid + 1]<<' '<<v[leftid]<<' '<<(v[rightid] - v[rightid - 1])<<'\n';
}
}
}
}
}
cout<<ans<<'\n';
return 0;
}
