#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 205;
const ll INF = 1e18;
int md[N*3],l;
ll dp[N][N][N][2];
int d(int x, int y)
{
return (min(abs(x-y),l-abs(x-y)));
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
int n,ans=1;
cin>>n>>l;
int a[n+1],t[n+1];
a[0]=t[0]=0;
for (int i=1;i<=n;++i)
{
md[i]=i;
cin>>a[i];
}
for (int i=1;i<=n;++i)
cin>>t[i];
for (int i=n+1;i<N*3;++i)
md[i]=md[i-n-1];
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[1][0][0][0]=0;
for (int i=1;i<=n+1;++i)
{
for (int j=1;j<=n;++j)
for (int k=0;k<=n;++k)
{
dp[i][k][md[k+j]][0]=min({dp[i-1][md[k+1]][md[k+j]][0]+d(a[md[k+1]],a[k]),dp[i-1][md[k+1]][md[k+j]][1]+d(a[md[k+j]],a[k])});
dp[i][k][md[k+j]][1]=min({dp[i-1][k][md[k+j-1]][1]+d(a[md[k+j]],a[md[k+j-1]]),dp[i-1][k][md[k+j-1]][0]+d(a[md[k+j]],a[k])});
if (dp[i][k][md[k+j]][0]>t[k])
dp[i][k][md[k+j]][0]=INF;
if (dp[i][k][md[k+j]][1]>t[md[k+j]])
dp[i][k][md[k+j]][1]=INF;
}
for (int j=1;j<=n;++j)
for (int k=0;k<=n;++k)
{
dp[i][k][md[k+j]][0]=min({dp[i][k][md[k+j]][0],dp[i][md[k+1]][md[k+j]][0]+d(a[md[k+1]],a[k]),dp[i][md[k+1]][md[k+j]][1]+d(a[md[k+j]],a[k])});
dp[i][k][md[k+j]][1]=min({dp[i][k][md[k+j]][1],dp[i][k][md[k+j-1]][1]+d(a[md[k+j]],a[md[k+j-1]]),dp[i][k][md[k+j-1]][0]+d(a[md[k+j]],a[k])});
}
}
for (int i=1;i<=n+1;++i)
for (int j=0;j<=n;++j)
for (int k=0;k<=n;++k)
if (min({dp[i][j][k][0],dp[i][j][k][1]})<INF)
ans=i;
cout<<ans-1;
return 0;
}
