#include<iostream>
#include<stack>
#include<map>
#include<vector>
#include<string>
#include<unordered_map>
#include <queue>
#include<cstring>
#include<limits.h>
#include<cmath>
#include<set>
#include<algorithm>
#include<bitset>
//#include "combo.h"
using namespace std;
#define ll long long
#define f first
#define endl "\n"
#define s second
#define pii pair<int,int>
#define ppii pair<int,pii>
#define pb push_back
#define p push
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define F(n) for(int i=0;i<n;i++)
#define lb lower_bound
#define ub upper_bound
#define fastio ios::sync_with_stdio(false);cin.tie(NULL);
using namespace std;
const int inf=1e9;
int dp[202][202][202][2],n,m;
int memo[202][202];
//at l r taken ,min time
int caldist(int u,int v){
//dist u->v;
if(u>v)swap(v,u);
if(memo[u][v]!=-1)return memo[u][v];
return memo[u][v]=min((v-u),m-v+u);
}
int32_t main(){
cin>>n>>m;
n++;
vector<pii>v(n);
v[0].f=0,v[0].s=0;
for(int i=1;i<n;i++)cin>>v[i].f;
for(int i=1;i<n;i++)cin>>v[i].s;
for(int i=0;i<=200;i++)for(int j=0;j<=200;j++){
memo[i][j]=-1;
for(int k=0;k<=200;k++)dp[i][j][k][0]=dp[i][j][k][1]=inf;
}
dp[0][0][0][0]=dp[0][0][0][1]=0;
for(int sz=0;sz<n-1;sz++){
int l,r=0,nr,nl;
l=(n-sz)%n;
bool yes=true;
while(yes){
if(l==0)yes=false;
nr=(r+1)%n;
nl=(l-1+n)%n;
for(int t=0;t<=n;t++){
if(dp[l][r][t][0]+caldist(v[nr].f,v[l].f)<=v[nr].s)dp[l][nr][t+1][1]=min(dp[l][nr][t+1][1],dp[l][r][t][0]+caldist(v[nr].f,v[l].f));
else dp[l][nr][t][1]=min(dp[l][nr][t][1],dp[l][r][t][0]+caldist(v[nr].f,v[l].f));//l to nr
if(dp[l][r][t][0]+caldist(v[l].f,v[nl].f)<=v[nl].s)dp[nl][r][t+1][0]=min(dp[nl][r][t+1][0],dp[l][r][t][0]+caldist(v[l].f,v[nl].f));
else dp[nl][r][t][0]=min(dp[nl][r][t][0],dp[l][r][t][0]+caldist(v[l].f,v[nl].f));
if(dp[l][r][t][1]+caldist(v[r].f,v[nl].f)<=v[nl].s)dp[nl][r][t+1][0]=min(dp[nl][r][t+1][0],dp[l][r][t][1]+caldist(v[r].f,v[nl].f));
else dp[nl][r][t][0]=min(dp[nl][r][t][0],dp[l][r][t][1]+caldist(v[r].f,v[nl].f));
if(dp[l][r][t][1]+caldist(v[nr].f,v[r].f)<=v[nr].s)dp[l][nr][t+1][1]=min(dp[l][nr][t+1][1],dp[l][r][t][1]+caldist(v[nr].f,v[r].f));
else dp[l][nr][t][1]=min(dp[l][nr][t][1],dp[l][r][t][1]+caldist(v[nr].f,v[r].f));
}
r=nr;
l=(l+1)%n;
}
}
int ans=0;
for(int i=0;i<=200;i++)for(int j=0;j<=200;j++)for(int k=0;k<=200;k++)for(int g=0;g<2;g++)if(dp[i][j][k][g]<inf)ans=max(ans,k);
cout<<ans;
}
