#include<bits/stdc++.h>
#define fi first
#define se second
#define pitem item*
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vl;
const int N=2e2+10;
const int SS=1<<19;
const int INFi=2e9;
const ll INFl=1e16;
const ll mod2=998244353;
const ll mod=1e9+7;
const ll mod3=1000696969;
const ll p=70032301;
const ull p2=913;
const int L=20;
ll t1[N],t2[N],n,dp[N][N][2][N],xd;
void solve(){
cin>>n>>xd;
for(int i=1;i<=n;i++) cin>>t1[i];
for(int i=1;i<=n;i++) cin>>t2[i];
for(int i=0;i<=n+1;i++){
for(int i2=0;i2<=n+1;i2++){
for(int i3=0;i3<2;i3++){
for(int i4=1;i4<=n+1;i4++) dp[i][i2][i3][i4]=-1;
dp[i][i2][i3][0]=INFl;
}
}
}
for(int i=n;i>=0;i--){
for(int i2=n-i;i2>=0;i2--){
for(int i3=0;i3<2;i3++){
for(int i4=1;i4<=n-(i+i2)+1;i4++){
if(!i3 and i==0) continue;
if(i3 and i2==0) continue;
if(i+i2==n){
if(!i3) dp[i][i2][i3][i4]=t2[i];
else dp[i][i2][i3][i4]=t2[n-i2+1];
continue;
}
if(!i3){
dp[i][i2][i3][i4]=max({dp[i][i2][i3][i4],
min(dp[i+1][i2][i3][i4-1]-(t1[i+1]-t1[i]),t2[i]),
dp[i+1][i2][i3][i4]-(t1[i+1]-t1[i]),
min(dp[i][i2+1][1][i4-1]-(t1[i]+xd-t1[n-i2]),t2[i]),
dp[i][i2+1][1][i4]-(t1[i]+xd-t1[n-i2])});
}else{
dp[i][i2][i3][i4]=max({dp[i][i2][i3][i4],
min(dp[i][i2+1][i3][i4-1]-(t1[n-i2+1]-t1[n-i2]),t2[n-i2+1]),
dp[i][i2+1][i3][i4]-(t1[n-i2+1]-t1[n-i2]),
min(dp[i+1][i2][0][i4-1]-(xd-t1[n-i2+1]+t1[i+1]),t2[n-i2+1]),
dp[i+1][i2][0][i4]-(xd-t1[n-i2+1]+t1[i+1])});
}
}
}
}
}
int res=0;
for(int i=1;i<=n;i++){
if(dp[1][0][0][i]-t1[1]>=0 or dp[0][1][1][i]-(xd-t1[n])>=0) res=i;
}
cout<<res<<"\n";
}
int main(){
ios_base::sync_with_stdio(0),cin.tie(0);
int tt=1;
while(tt--) solve();
}
