#include <bits/stdc++.h>
#ifndef DEBUG
#include "shortcut.h"
#endif
using namespace std;
template<typename T>
using V = vector<T>;
using ll = long long;
using vi = V<int>;
using vl = V<ll>;
using pi = pair<int,int>;
using pl = pair<ll, ll>;
constexpr int INF = 1e9 + 7;
#define ckmax(a,b) a = max(a,b)
#define ckmin(a,b) a = min(a,b)
#define F0R(i, n) for (int i = 0; i < n;i++)
#define FOR(i, j , n) for (int i = j ;i < n;i++)
int n;
pl findFar(ll a, ll l, ll r, vl d, vl leng) {
pl results = {0,a};
ll path = 0;
for (ll i = a + 1; i <= r; ++i) {
path += leng[i - 1];
ckmax(results, make_pair(path + d[i],i));
}
path = 0;
for (ll i = a - 1; i >= l; --i) {
path += leng[i];
ckmax(results, make_pair(path + d[i],i));
}
return results;
}
ll solveSep(ll a, ll b, vl d, vl leng) {
if (a == 0 && b == 1) {
int stop = 25;
}
ll x = findFar(a, a, b , d, leng).second;
pl results = findFar(x, a, b, d, leng);
return results.first + d[x];
}
ll test(ll a, ll b, vl leng, vl d, ll c) {
ll cycle = c;
FOR(i, a, b) {
cycle += leng[i];
}
ll ans = 0;
ll f1 = solveSep(0, a, d, leng);
if (a - 0 > 0) ckmax(ans, f1);
if (n - 1 - b > 0) ckmax(ans, solveSep(b, n - 1, d, leng));
ll farA = d[a], farB = d[b], distA = 0, distB = 0;
for (int i = a - 1; i >= 0; --i) {
distA += leng[i];
ckmax(farA, distA + d[i]);
}
for (int i = b + 1; i < n; ++i) {
distB += leng[i - 1];
ckmax(farB, distB + d[i]);
}
d[a] = farA;
d[b] = farB;
FOR(i, a, b + 1) {
ll dist = 0;
FOR(j, i + 1, b + 1) {
dist += leng[j - 1];
ckmax(ans, min(dist, cycle - dist) + d[j] + d[i]);
}
}
if (ans < 15) {
int stop = 25;
}
return ans;
}
long long find_shortcut(int N, std::vector<int> l2, std::vector <int> d2, int c) {
vl l(N - 1), d(N);
F0R(i, N) {
if (i != N - 1) l[i] = l2[i];
d[i] = d2[i];
}
n = N;
ll ans = 1e18;
F0R(i, N) {
FOR(j,i + 1, N) {
ckmin(ans, test(i, j ,l, d, c));
}
}
return ans;
}
#if DEBUG
int main()
{
int n, c;
assert(2 == scanf("%d%d", &n, &c));
std::vector<int> l(n - 1);
std::vector<int> d(n);
for (int i = 0; i < n - 1; i++)
assert(1 == scanf("%d", &l[i]));
for (int i = 0; i < n; i++)
assert(1 == scanf("%d", &d[i]));
long long t = find_shortcut(n, l, d, c);
printf("%lld\n", t);
return 0;
}
#endif
