#include<bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 3e5 + 5;
array<int, 3> b[maxn];
struct SegmentTree{
int st[4 * maxn], lazy[4 * maxn];
void add(int id, int val){
st[id] += val;
lazy[id] += val;
}
void push(int id){
if (lazy[id]){
add(id * 2, lazy[id]);
add(id * 2 + 1, lazy[id]);
lazy[id] = 0;
}
}
void upd(int id, int l, int r, int u, int v, int val){
if (r < u || l > v) return;
if (u <= l && r <= v){
add(id, val);
return;
}
push(id);
int mid = (l + r) / 2;
upd(id * 2, l, mid, u, v, val);
upd(id * 2 + 1, mid + 1, r, u, v, val);
st[id] = min(st[id * 2], st[id * 2 + 1]);
}
int get(int id, int l, int r, int u, int v){
if (r < u || l > v) return 1e18;
if (u <= l && r <= v) return st[id];
push(id);
int mid = (l + r) / 2;
return min(get(id * 2, l, mid, u, v), get(id * 2 + 1, mid + 1, r, u, v));
}
} tree;
void solve(){
int n, d; cin >> n >> d;
vector<int> compress;
for (int i = 1; i <= n; i++){
int x, a, bb; cin >> x >> a >> bb;
b[i] = {bb, x, a};
compress.emplace_back(x);
}
sort(compress.begin(), compress.end());
compress.resize(unique(compress.begin(), compress.end()) - compress.begin());
sort(b + 1, b + n + 1, greater<>());
set<pair<int, int>> s;
s.insert({0, 0});
s.insert({n + 1, d});
tree.upd(1, 0, n, 1, n, d);
int ans = d;
b[0][0] = d;
for (int i = 1; i <= n; i++){
int pos = upper_bound(compress.begin(), compress.end(), b[i][1]) - compress.begin();
auto it = s.lower_bound({pos, b[i][1]});
tree.upd(1, 0, n, 0, n, b[i][0] - b[i - 1][0]);
tree.upd(1, 0, n, pos, n, b[i][2]);
if ((*it).first != pos){
int id_pre = (*prev(it)).first;
int pos_nxt = (*it).second;
tree.upd(1, 0, n, id_pre, id_pre, pos_nxt - b[i][1]);
tree.upd(1, 0, n, pos, pos, -pos_nxt);
}
s.insert({pos, b[i][1]});
int k = tree.get(1, 0, n, 0, n);
if(k >= 0) ans = min(ans, b[i][0] - k);
}
cout << ans;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
freopen("FFUEL.inp", "r", stdin);
freopen("FFUEL.out", "w", stdout);
solve();
}
