#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define st first
#define nd second
typedef long long ll;
typedef long double ld;
const ll I = 10'000'000'000'000'000LL;
const int II = 2'000'000'000;
const ll M = 1000'000'007LL;
const int N = 207;
ll dis[N], m;
int n;
ll tab[N];
ll dp[N][N][N][2];
ll D(int a, int b)
{
if(a > b) swap(a, b);
return min(dis[b] - dis[a], m - (dis[b] - dis[a]));
}
ll Licz(int r, int a, int b, int x)
{
int a1, b1;
ll ans = I;
a1 = a + 1; b1 = b - 1;
if(a1 > n) a1 = 1;
if(b1 < 1) b1 = n;
if(r == 0)
{
//if(a == 4 && b == 5)
//{
//cout << a << " " << b << " " << a1 << " " << b1 << "\n";
//}
ans = dp[a1][b][x][0] + D(a, a1);
ans = min(ans, dp[a1][b][x][1] + D(a, b));
return ans;
}
ans = dp[a][b1][x][0] + D(a, b);
ans = min(ans, dp[a][b1][x][1] + D(b1, b));
return ans;
}
void Solve()
{
cin >> n >> m;
for(int i = 1; i <= n; ++i)
cin >> dis[i];
for(int i = 1; i <= n; ++i)
cin >> tab[i];
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
for(int k = 0; k <= n; ++k)
for(int r = 0; r < 2; ++r)
dp[i][j][k][r] = I;
dp[1][1][0][0] = min(dis[1], m - dis[1]);
dp[n][n][0][0] = min(dis[n], m - dis[n]);
if(dp[1][1][0][0] <= tab[0]) dp[1][1][1][0] = dp[1][1][0][0];
if(dp[n][n][0][0] <= tab[n]) dp[n][n][1][0] = dp[n][n][0][0];
dp[1][1][0][1] = dp[1][1][0][0]; dp[1][1][1][1] = dp[1][1][1][0];
dp[n][n][0][1] = dp[n][n][0][0]; dp[n][n][1][1] = dp[n][n][1][0];
int answer = 0;
if(dp[1][1][1][0] < I || dp[n][n][1][0] < I) answer = 1;
//cout << dp[n][n][0][0] << "\n";
for(int d = 2; d <= n; ++d)
{
for(int i = 1; i <= n; ++i)
{
int j = i + d - 1;
if(j > n) j -= n;
for(int l = 0; l <= n; ++l)
{
dp[i][j][l][0] = Licz(0, i, j, l);
dp[i][j][l][1] = Licz(1, i, j, l);
}
for(int l = n - 1; l >= 0; --l)
{
if(dp[i][j][l][0] <= tab[i]) dp[i][j][l + 1][0] = min(dp[i][j][l + 1][0], dp[i][j][l][0]);
if(dp[i][j][l][1] <= tab[j]) dp[i][j][l + 1][1] = min(dp[i][j][l + 1][1], dp[i][j][l][1]);
}
for(int l = 0; l <= n; ++l)
for(int r = 0; r < 2; ++r)
{
dp[i][j][l][r] = min(dp[i][j][l][r], I);
if(dp[i][j][l][r] < I)
{
// cout << "DP: " << i << " " << j << " " << l << " " << r << " " << dp[i][j][l][r] << "\n";
answer = max(answer, l);
}
}
}
}
cout << answer << "\n";
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//int t; cin >> t;
//while(t--)
Solve();
return 0;
}
