#include <cstdio>
#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <set>
#include <map>
#include <utility>
using namespace std;
int ans = 0;
bool vis[400][400][2];
long long dp[400][400][201][2];
long long grid[400];
long long stamptime[400];
int nums; long long len;
int dplen, dp0len, dp00len;
void findans(int l, int r, int end) {
if (vis[l][r][end]) return;
vis[l][r][end] = true;
if (l==r) {
dp[l][l][0][end] = abs(len-grid[l]);
if (abs(len-grid[l]) <= stamptime[l])
dp[l][l][1][end] = abs(len-grid[l]);
} else if (end == 0) {
for (int i = l+1; i <= l+1; i++) {
findans(i, r, 0); findans(i, r, 1);
long distl = grid[i]-grid[l];
long distr = grid[r]-grid[l];
for (int j = 0; j < dp00len; j++) {
if (dp[i][r][j][0]+distl <= stamptime[l]) {
if (j != dp00len-1)
dp[l][r][j+1][0] = min(dp[l][r][j+1][0],
dp[i][r][j][0]+distl);
} else
dp[l][r][j][0] = min(dp[l][r][j][0],
dp[i][r][j][0]+distl);
if (dp[i][r][j][1]+distr <= stamptime[l]) {
if (j != dp00len-1)
dp[l][r][j+1][0] = min(dp[l][r][j+1][0],
dp[i][r][j][1]+distr);
} else
dp[l][r][j][0] = min(dp[l][r][j][0],
dp[i][r][j][1]+distr);
}
for (int j = dp00len-2; j >= 0; j--) {
dp[l][r][j][0] = min(dp[l][r][j][0],
dp[l][r][j+1][0]);
}
}
} else {
for (int i = r-1; i >= r-1; i--) {
findans(l, i, 0); findans(l, i, 1);
long distl = grid[r]-grid[l];
long distr = grid[r]-grid[i];
for (int j = 0; j < dp00len; j++) {
if (dp[l][i][j][0]+distl <= stamptime[r]) {
if (j != dp00len-1)
dp[l][r][j+1][1] = min(dp[l][r][j+1][1],
dp[l][i][j][0]+distl);
} else
dp[l][r][j][1] = min(dp[l][r][j][1],
dp[l][i][j][0]+distl);
if (dp[l][i][j][1]+distr <= stamptime[r]) {
if (j != dp00len-1)
dp[l][r][j+1][1] = min(dp[l][r][j+1][1],
dp[l][i][j][1]+distr);
} else
dp[l][r][j][1] = min(dp[l][r][j][1],
dp[l][i][j][1]+distr);
}
for (int j = dp00len-2; j >= 0; j--) {
dp[l][r][j][1] = min(dp[l][r][j][1],
dp[l][r][j+1][1]);
}
}
}
for (int i = 0; i < dp00len; i++) {
if (dp[l][r][i][end] != (((long long) 2*1e9)*3)) {
ans = max(ans, i);
}
}
}
int main() {
cin >> nums >> len;
dplen = nums*2; dp0len = nums*2; dp00len = nums+1;
for (int i = 0; i < nums; i++) {
int val; cin >> val;
grid[i] = val; grid[nums+i] = val+len;
}
for (int i = 0; i < nums; i++) {
int val; cin >> val;
stamptime[i] = val; stamptime[nums+i] = val;
}
for (int i = 0; i < dplen; i++) {
for (int j = 0; j < dp0len; j++) {
for (int k = 0; k < dp00len; k++) {
for (int l = 0; l < 2; l++) {
dp[i][j][k][l] = ((long long) 2*1e9)*3;
}
}
}
}
for (int i = 0; i <= nums; i++) {
findans(i, i+nums-1, 0);
findans(i, i+nums-1, 1);
}
cout << (ans) << "\n";
}
