#include <bits/stdc++.h>
using namespace std;
#define POPCOUNT(n) (__builtin_popcountll((n)))
#define CLZ(n) (__builtin_clzll((n)))
#define CTZ(n) (__builtin_ctzll((n)))
#define LOG(n) (63 - __builtin_clzll((n)))
#define BIT(n, i) (((n) >> (i)) & 1ll)
#define MASK(i) (1ll << (i))
#define FLIP(n, i) ((n) ^ (1ll << (i)))
#define ON(n, i) ((n) | MASK(i))
#define OFF(n, i) ((n) & ~MASK(i))
#define Int __int128
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef pair<long long, int> pli;
typedef pair<int, long long> pil;
typedef vector<pair<int, int>> vii;
typedef vector<pair<long long, long long>> vll;
typedef vector<pair<long long, int>> vli;
typedef vector<pair<int, long long>> vil;
template <class T1, class T2> bool maximize(T1 &x, T2 y) {
if (x < y) {
x = y;
return true;
}
return false;
}
template <class T1, class T2> bool minimize(T1 &x, T2 y) {
if (x > y) {
x = y;
return true;
}
return false;
}
template <class T> void remove_duplicate(vector<T> &ve) {
sort (ve.begin(), ve.end());
ve.resize(unique(ve.begin(), ve.end()) - ve.begin());
}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
long long random(long long l, long long r) {
return uniform_int_distribution<long long>(l, r)(rng);
}
unsigned long long random(unsigned long long l, unsigned long long r) {
return uniform_int_distribution<unsigned long long>(l, r)(rng);
}
template <class T> T random(T r) {
return rng() % r;
}
const int N = 1e6 + 5;
const int MOD = 1e9 + 7;
const int inf = 1e9;
const long long INF = 1e18;
int n, m;
int a[N], b[N], c[N], d[N];
struct SegmentTree {
vector<ll> nodes;
int n;
SegmentTree() {}
void resize(int _n) {
n = _n; nodes.assign(2 * n + 5, INF);
}
void update(int p, ll val) {
for (minimize(nodes[p += n], val); p >>= 1;)
nodes[p] = min(nodes[p << 1], nodes[p << 1 | 1]);
}
ll get(int l, int r) {
ll ans = INF;
for (l += n, r += n + 1; l < r; l >>= 1, r >>= 1) {
if (l & 1) minimize(ans, nodes[l++]);
if (r & 1) minimize(ans, nodes[--r]);
}
return ans;
}
} dpLeft, dpRight;
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cin >> n >> m;
vector<int> values;
for (int i = 1; i <= n; ++i) {
cin >> a[i] >> b[i] >> c[i] >> d[i];
values.emplace_back(a[i]);
values.emplace_back(b[i]);
values.emplace_back(c[i]);
}
values.emplace_back(1);
values.emplace_back(m);
remove_duplicate(values);
auto cmp = [&](int x) {
return lower_bound(values.begin(), values.end(), x) - values.begin() + 1;
};
// the ci of chosen segments create a V shape
// -----.---- ----.----
// ---.----- ---.---
// -------.------
dpLeft.resize(values.size());
dpRight.resize(values.size());
dpLeft.update(1, 0);
dpRight.update(values.size(), 0);
ll ans = INF;
for (int i = 1; i <= n; ++i) {
int l = cmp(a[i]), r = cmp(b[i]), p = cmp(c[i]);
ll costLeft = dpLeft.get(l, r);
ll costRight = dpRight.get(l, r);
minimize(ans, costLeft + costRight + d[i]);
dpLeft.update(p, costLeft + d[i]);
dpRight.update(p, costRight + d[i]);
}
cout << ans;
return 0;
}
