#include <bits/stdc++.h>
using namespace std;
template <typename T>
struct segment_tree{
	int N;
	vector<T> ST;
	segment_tree(int n){
		N = 1;
		while (N < n){
			N *= 2;
		}
		ST = vector<T>(N * 2 - 1, 0);
	}
	T operator [](int k){
		return ST[N - 1 + k];
	}
	void update(int k, T x){
		k += N - 1;
		ST[k] = x;
		while (k > 0){
			k = (k - 1) / 2;
			ST[k] = max(ST[k * 2 + 1], ST[k * 2 + 2]);
		}
	}
	T range_max(int L, int R, int i, int l, int r){
		if (R <= l || r <= L){
			return 0;
		} else if (L <= l && r <= R){
			return ST[i];
		} else {
			int m = (l + r) / 2;
			return max(range_max(L, R, i * 2 + 1, l, m), range_max(L, R, i * 2 + 2, m, r));
		}
	}
	T range_max(int L, int R){
		return range_max(L, R, 0, 0, N);
	}
	T all(){
		return ST[0];
	}
};
int main(){
  int N;
  cin >> N;
  vector<int> T(N), X(N), V(N);
  for (int i = 0; i < N; i++){
    cin >> T[i] >> X[i] >> V[i];
  }
  vector<long long> A(N), B(N);
  for (int i = 0; i < N; i++){
    A[i] = T[i] + X[i];
    B[i] = T[i] - X[i];
  }
  vector<long long> A2 = A;
  sort(A2.begin(), A2.end());
  A2.erase(unique(A2.begin(), A2.end()), A2.end());
  for (int i = 0; i < N; i++){
    A[i] = lower_bound(A2.begin(), A2.end(), A[i]) - A2.begin();
  }
  vector<long long> B2 = B;
  sort(B2.begin(), B2.end());
  B2.erase(unique(B2.begin(), B2.end()), B2.end());
  for (int i = 0; i < N; i++){
    B[i] = lower_bound(B2.begin(), B2.end(), B[i]) - B2.begin();
  }
  int cnt1 = A2.size(), cnt2 = B2.size();
  vector<vector<pair<int, int>>> P(cnt1);
  for (int i = 0; i < N; i++){
    if (A2[A[i]] >= 0 && B2[B[i]] >= 0){
      P[A[i]].push_back(make_pair(B[i], i));
    }
  }
  segment_tree<long long> dp(cnt2);
  for (int i = 0; i < cnt1; i++){
    sort(P[i].begin(), P[i].end());
    int cnt = P[i].size();
    for (int j = 0; j < cnt; j++){
      int pos = P[i][j].first;
      int value = V[P[i][j].second];
      dp.update(pos, dp.range_max(0, pos + 1) + value);
    }
  }
  cout << dp.all() << endl;
}