#include <iostream>
#include <cmath>
#include <algorithm>
using namespace std;
long long X[202];
long long T[202];
long long L;
long long dist(int a, int b)
{
return min( abs(X[a] - X[b]), min(X[a], abs(L - X[a])) + min(X[b], abs(L - X[b])) );
}
int main()
{
long long inf = 1;
for(int i = 1; i <= 18; i++) inf = inf * 10LL;
int N;
cin >> N >> L;
for(int i = 1; i <= N; i++) cin >> X[i];
for(int i = 1; i <= N; i++) cin >> T[i];
long long dp_left[N+2][N+2][N+2], dp_right[N+2][N+2][N+2];
for(int i = 0; i <= N+1; i++)
for(int j = 0; j <= N+1; j++)
for(int k = 0; k <= N+1; k++)
dp_left[i][j][k] = dp_right[i][j][k] = inf;
//minimum time needed to collect k stamps from among j, i+1, ... N, 1, .... i and end up at left/right.
X[0] = X[N+1] = 0;
int res = 0;
dp_left[0][N+1][0] = dp_right[0][N+1][0] = 0;
for(int k = 0; k <= N; k++)
{
for(int i = 0; i <= N; i++)
{
for(int j = N+1; j > i; j--)
{
//don't collect
if(j < N+1)
{
dp_left[i][j][k] = min(dp_left[i][j][k], dp_left[i][j+1][k] + dist(j, j+1));
dp_left[i][j][k] = min(dp_left[i][j][k], dp_right[i][j+1][k] + dist(i, j));
}
if(i > 0)
{
dp_right[i][j][k] = min(dp_right[i][j][k], dp_right[i-1][j][k] + dist(i, i-1));
dp_right[i][j][k] = min(dp_right[i][j][k], dp_left[i-1][j][k] + dist(i, j));
}
if(k == 0) continue;
//collect
if(j < N+1)
{
if(dp_left[i][j+1][k-1] + dist(j+1, j) <= T[j])
dp_left[i][j][k] = min(dp_left[i][j][k], dp_left[i][j+1][k-1] + dist(j+1, j));
if(dp_right[i][j+1][k-1] + dist(i, j) <= T[j])
dp_left[i][j][k] = min(dp_left[i][j][k], dp_right[i][j+1][k-1] + dist(i, j));
}
if(i > 0)
{
if(dp_right[i-1][j][k-1] + dist(i-1, i) <= T[i])
dp_right[i][j][k] = min(dp_right[i][j][k], dp_right[i-1][j][k-1] + dist(i-1, i));
if(dp_left[i-1][j][k-1] + dist(i, j) <= T[i])
dp_right[i][j][k] = min(dp_right[i][j][k], dp_left[i-1][j][k-1] + dist(i, j));
}
if(dp_left[i][j][k] != inf) res = max(res, k);
if(dp_right[i][j][k] != inf) res = max(res, k);
// cout << i << ' ' << j << ' ' << k << " -> " << dp_left[i][j][k] << ' ' << dp_right[i][j][k] << '\n';
}
}
}
cout << res << '\n';
}
