#include <bits/stdc++.h>
using namespace std;
long long int dp[205][205][205][2];
int n,L,x[400],t[400];
const long long int INF = 1e18;
int dist(int l,int r){
if(r >= l)return x[r] - x[l];
return L-x[l] + x[r];
}
int main()
{
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+1;k++)dp[i][j][k][0] = dp[i][j][k][1] = INF;
}
t[0] = -1;
dp[0][0][0][0] = 0;
n++;
int ans = 0;
for(int i=0;i<n;i++){
for(int l=0;l<n;l++){
for(int k=0;k<=n;k++){
int r = (l+i)%n;
for(int c=0;c<2;c++){
if(dp[l][r][k][c] == INF)continue;
//cout<<l<<" "<<r<<" "<<k<<" "<<c<<" "<<dp[l][r][k][c]<<'\n';
ans = max(ans,k);
int s = c?r:l;
int ln = (l-1+n)%n;
int d = dist(ln,s);
long long int v = dp[l][r][k][c] + d;
dp[ln][r][k][0] = min(dp[ln][r][k][0],v);
if(t[ln] >= v)dp[ln][r][k+1][0] = min(dp[ln][r][k+1][0],v);
int rn = (r+1)%n;
d = dist(s,rn);
v = dp[l][r][k][c] + d;
dp[l][rn][k][1] = min(dp[l][rn][k][1],v);
if(t[rn] >= v)dp[l][rn][k+1][1] = min(dp[l][rn][k+1][1],v);
}
}
}
}
cout<<ans<<'\n';
}
