#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int, int>
const int INF = 1e18;
const int MAX_N = 202;
int N, L;
int X[MAX_N], T[MAX_N];
pii dp[MAX_N][MAX_N][MAX_N];
int dist(int a, int b){
if(a>b){
return (b-a+L)%L;
}
return a-b;
}
void push_val(int left, int right, int has){
int sz = dist(X[left],X[right]);
dp[left][right][has].first = min(dp[left][right][has].first, dp[left][right][has].second+sz);
dp[left][right][has].second = min(dp[left][right][has].second, dp[left][right][has].first+sz);
if(left-right>1){
int new_time = dp[left][right][has].first + abs(X[left-1] - X[left]);
if(new_time<=T[left-1]){
dp[left-1][right][has+1].first = min(dp[left-1][right][has+1].first , new_time);
}
else{
dp[left-1][right][has].first = min(dp[left-1][right][has].first , new_time);
}
new_time = dp[left][right][has].second + abs(X[right+1] - X[right]);
if(new_time<=T[right+1]){
dp[left][right+1][has+1].second = min(dp[left][right+1][has+1].second , new_time);
}
else{
dp[left][right+1][has].second = min(dp[left][right+1][has].second , new_time);
}
}
}
signed main(){
fill(&dp[0][0][0], &dp[MAX_N-1][MAX_N-1][MAX_N-1] +1, pii(INF, INF));
cin>>N>>L;
N++;
X[0]= 0;
T[0] = -1;
for(int i = 1; i<N; i++){
cin>>X[i];
}
for(int i =1; i<N; i++){
cin>>T[i];
}
X[N] = L;
T[N] = -1;
dp[N][0][0] = pii(0, 0);
for(int l = N; l>0; l--){
for(int r = 0; r<l; r++){
for(int has = 0; has<N; has++){
push_val(l, r, has);
//cout<<l<<" "<<r<<" "<<has<<" "<<dp[l][r][has].first<<" "<<dp[l][r][has].second<<endl;
}
}
}
int res =0;
for(int l = N; l>0; l--){
for(int r = 0; r<l; r++){
for(int has = 0; has<N; has++){
if(dp[l][r][has].first<INF || dp[l][r][has].second<INF){
res = max(res, has);
}
}
}
}
cout<<res<<endl;
}
