#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define sz(x) (int)x.size()
#define ALL(v) v.begin(),v.end()
#define MASK(k) (1LL << (k))
#define BIT(x, i) (((x) >> (i)) & 1)
#define oo (ll)1e18
#define INF (ll)1e9
#define MOD (ll)(998244353)
using namespace std;
template<class T1, class T2>
bool maximize(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}
template<class T1, class T2>
bool minimize(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}
template<class T1, class T2>
void add(T1 &a, T2 b){a += b; if(a >= MOD) a -= MOD;}
template<class T1, class T2>
void sub(T1 &a, T2 b){a -= b; if(a < 0) a += MOD;}
template<class T>
void cps(T &v){sort(ALL(v)); v.resize(unique(ALL(v)) - v.begin());}
const int MAX = 5e5 + 10;
int N, D;
tuple<int, int, int> a[MAX];
bool OK(int x){
ll cur = x;
for(int i=1; i<=N+1; i++){
cur -= (get<0>(a[i]) - get<0>(a[i - 1]));
if(cur < 0) return false;
if(x <= get<2>(a[i])) maximize(cur, get<1>(a[i]));
}
return true;
}
void solve(){
cin >> N >> D;
for(int i=1; i<=N; i++){
cin >> get<0>(a[i]) >> get<1>(a[i]) >> get<2>(a[i]);
}
sort(a + 1, a + N + 1);
a[N + 1] = make_tuple(D, 0, 0);
int l = 1, r = D;
while(l < r){
int m = (l + r) >> 1;
if(OK(m)){
r = m;
}
else{
l = m + 1;
}
}
cout << r << '\n';
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen("split.inp", "r", stdin);
// freopen("split.out", "w", stdout);
int tt = 1;
// cin >> tt;
while(tt--){
solve();
}
return 0;
}
