#include <bits/stdc++.h>
using namespace std;
using ll = long long;
struct Station {
int x, a, b, id;
};
struct SegmentTree {
int n;
vector<ll> tree, lazy;
SegmentTree(const vector<ll>& base) {
n = base.size();
tree.assign(4 * n, 0);
lazy.assign(4 * n, 0);
build(1, 0, n - 1, base);
}
void build(int node, int start, int end, const vector<ll>& base) {
if (start == end) {
tree[node] = base[start];
return;
}
int mid = (start + end) / 2;
build(2 * node, start, mid, base);
build(2 * node + 1, mid + 1, end, base);
tree[node] = min(tree[2 * node], tree[2 * node + 1]);
}
void push(int node) {
if (lazy[node] != 0) {
tree[2 * node] += lazy[node];
lazy[2 * node] += lazy[node];
tree[2 * node + 1] += lazy[node];
lazy[2 * node + 1] += lazy[node];
lazy[node] = 0;
}
}
void update(int node, int start, int end, int l, int r, ll val) {
if (start > end || start > r || end < l) return;
if (start >= l && end <= r) {
tree[node] += val;
lazy[node] += val;
return;
}
push(node);
int mid = (start + end) / 2;
update(2 * node, start, mid, l, r, val);
update(2 * node + 1, mid + 1, end, l, r, val);
tree[node] = min(tree[2 * node], tree[2 * node + 1]);
}
ll query_all() { return tree[1]; }
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
ll d;
cin >> n >> d;
vector<Station> X(n);
vector<pair<ll, int>> coords;
for(int i = 0; i < n; i++) {
cin >> X[i].x >> X[i].a >> X[i].b;
X[i].id = i;
coords.push_back({X[i].x, i});
}
coords.push_back({d, n});
sort(coords.begin(), coords.end());
vector<int> mpos(n + 1);
int cnt = n;
for(int i = n; ~i; i--) {
if (i < n && coords[i].first != coords[i + 1].first) {
cnt = i + 1;
}
mpos[coords[i].second] = cnt;
}
vector<tuple<ll, ll, int>> b;
for (int i = 0; i < n; i++) {
b.emplace_back(X[i].b, X[i].a, mpos[i]);
}
b.emplace_back(1e12, 0, mpos[n]);
sort(b.begin(), b.end());
vector<ll> base(n + 1);
for(int i = 0; i <= n; i++)
base[i] = -coords[i].first;
SegmentTree st(base);
for (int i = 0; i < n; i++)
st.update(1, 0, n, get<2>(b[i]), n, get<1>(b[i]));
ll ans = d;
int ptr = 0;
for(int i = 0; i <= n; i++) {
ll curr = get<0>(b[i]);
ll prev = (i == 0) ? 0 : get<0>(b[i - 1]);
st.update(1, 0, n, 0, n, curr - prev);
if (i < n && curr == get<0>(b[i + 1])) continue;
while (get<0>(b[ptr]) != curr) {
st.update(1, 0, n, get<2>(b[ptr]), n, -get<1>(b[ptr]));
ptr++;
}
ll min_val = st.query_all();
if (min_val >= 0) {
ans = min(ans, curr - min_val);
}
}
cout << ans;
return 0;
}
