#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#define int long long
const int MAXN = 202;
int per;
int dp[MAXN][MAXN][MAXN][2];
int give_best(int l, int r)
{
return std::min(std::abs(r - l), per - std::abs(r - l));
}
signed
main()
{
std::ios::sync_with_stdio(false);
std::cin.tie(0);
int n;
std::cin >> n;
std::cin >> per;
std::vector<int> x;
x.push_back(0);
std::vector<int> t;
t.push_back(1e9);
for (int i = 0; i < n; i++)
{
int help;
std::cin >> help;
x.push_back(help);
}
for (int i = 0; i < n; i++)
{
int help;
std::cin >> help;
t.push_back(help);
}
if (n == 1)
{
if (t[1] >= std::min(per - x[1], x[1]))
{
std::cout << 1;
}
else
{
std::cout << 0;
}
return 0;
}
for (int l = 0; l <= n; l++)
{
for (int r = 0; r <= n; r++)
{
for (int j = 0; j <= n; j++)
{
dp[l][r][j][0] = 1e13;
dp[l][r][j][1] = 1e13;
}
}
}
int max = 0;
dp[1][n][0][0] = 0;
dp[1][n][0][1] = 0;
for (int len = n - 1; len >= 0; len--)
{
for (int l = 1; l <= n - len; l++)
{
int r = l + len - 1;
for (int j = 0; j <= (n - len); j++)
{
if (j > 0 && l > 1)
{
if (dp[l - 1][r][j - 1][0] + give_best(x[l - 1], x[l - 2]) <= t[l - 1])
{
dp[l][r][j][0] = std::min(dp[l][r][j][0],
dp[l - 1][r][j - 1][0] +
give_best(x[l - 1], x[l - 2]));
}
else
{
dp[l][r][j][0] = std::min(dp[l][r][j][0],
dp[l - 1][r][j][0] +
give_best(x[l - 1], x[l - 2]));
}
}
else if (l > 1)
{
dp[l][r][j][0] = std::min(dp[l][r][j][0],
dp[l - 1][r][j][0] +
give_best(x[l - 1], x[l - 2]));
}
if (j > 0 && r < n)
{
// std::cout << t[r + 1] << ' ' << give_best(x[(r + 2) % (n + 1)], x[r + 1]) << std::endl;
if (dp[l][r + 1][j - 1][1] +
give_best(x[(r + 2) % (n + 1)], x[r + 1]) <=
t[r + 1])
{
dp[l][r][j][1] = std::min(dp[l][r][j][1],
dp[l][r + 1][j - 1][1] +
give_best(x[(r + 2) % (n + 1)], x[r + 1]));
}
else
{
dp[l][r][j][1] = std::min(dp[l][r][j][1],
dp[l][r + 1][j][1] +
give_best(x[(r + 2) % (n + 1)], x[r + 1]));
}
}
else if (r < n)
{
dp[l][r][j][1] = std::min(dp[l][r][j][1],
dp[l][r + 1][j][1] +
give_best(x[(r + 2) % (n + 1)], x[r + 1]));
}
if (dp[l][r][j][0] < dp[l][r][j][1])
{
int help = (r + 1) % (n + 1);
int help1 = l - 1;
dp[l][r][j][1] = std::min(dp[l][r][j][1],
dp[l][r][j][0] + give_best(x[help], x[help1]));
}
else
{
int help = (r + 1) % (n + 1);
int help1 = l - 1;
dp[l][r][j][0] = std::min(dp[l][r][j][0],
dp[l][r][j][1] + give_best(x[help], x[help1]));
}
if (dp[l][r][j][0] < 1e13 || dp[l][r][j][1] < 1e13)
{
max = std::max(max, j);
}
}
}
}
std::cout << max;
}
