#include <bits/stdc++.h>
using namespace std ;
const int inf = 2e9 ;
const int MAX = 210 ;
long long X[MAX] , T[MAX] ;
int n ;
long long L ;
long long dp[MAX][MAX][MAX][2] ;
long long dist(int i , int j , int a , int b)
{
if(b == 0)
{
if(a == 0)
return (X[i] - X[i-1]) ;
else
return (L - X[j] + X[i-1]) ;
}
else
{
if(a == 1)
return (X[j+1] - X[j]) ;
else
return (X[i] + L - X[j+1]) ;
}
}
int main()
{
ios_base::sync_with_stdio(0) ;
cin.tie(0) ;
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+1 ; ++i)
{
for(int j = 0 ; j <= n+1 ; ++j)
{
for(int taken = 1 ; taken <= n+1 ; ++taken)
{
for(int a = 0 ; a <= 1 ; ++a)
dp[i][j][taken][a] = inf ;
}
}
}
X[n+1] = L ;
int ans = 0 ;
for(int i = 1 ; i <= n ; ++i)
{
for(int j = n ; j >= i ; --j)
{
for(int taken = 0 ; taken <= n ; ++taken)
{
for(int a = 0 ; a <= 1 ; ++a)
{
long long x , y ;
x = dp[i-1][j][taken][0] + dist(i , j , a , 0) ;
y = dp[i][j+1][taken][1] + dist(i , j , a , 1) ;
dp[i][j][taken][a] = min(x , y) ;
if(taken)
{
x = dp[i-1][j][taken-1][0] + dist(i , j , a , 0) ;
y = dp[i][j+1][taken-1][1] + dist(i , j , a , 1) ;
if((a == 0 && min(x , y) <= T[i]) || (a == 1 && min(x , y) <= T[j]))
{
dp[i][j][taken][a] = min(dp[i][j][taken][a] , min(x , y)) ;
ans = max(ans , taken) ;
}
}
}
}
}
}
return cout<<ans<<"\n" , 0 ;
}
