#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0;i < (n);i++)
using ll = long long;
using P =pair<int,int>;
using T = tuple<int,int,int>;
ll INF = 1LL << 60;
int LEN = 1 << 20;
vector<ll> seg(2*LEN,0);
void add(int ind,ll val){
  ind += LEN;
  seg[ind] = max<ll>(val,seg[ind]);
  while(ind > 0){
    ind /= 2;
    seg[ind] = max<ll>(seg[ind*2],seg[ind*2 + 1]);
  }
}
ll maxim(int l,int r){
  l += LEN;
  r += LEN;
  ll ans = 0;
  while(l < r){
    if(l & 1 )ans = max<ll>(ans,seg[l++]);
    l /= 2;
    if(r & 1)ans = max<ll>(ans,seg[--r]);
    r /= 2;
  }
  return ans;
}
int main(){
  int n;
  cin >> n;
  vector<T> items(n);
  vector<int> X,Y;
  rep(i,n){
    int t,x,v;
    cin >> t >> x >> v;
    int x2 = (t-x);
    int y2 = (t+x);
    X.push_back(x2);
    Y.push_back(y2);
    items[i] = make_tuple(x2,y2,v);
  }
  sort(X.begin(),X.end());
  sort(Y.begin(),Y.end());
  map<int,int> mpX,mpY;
  rep(i,n){
    mpX[X[i]] = lower_bound(X.begin(),X.end(),X[i]) - X.begin() + 1;
    mpY[Y[i]] = lower_bound(Y.begin(),Y.end(),Y[i]) - Y.begin() + 1;
    if(X[i] < 0)mpX[X[i]] = -1;
    if(Y[i] < 0)mpY[Y[i]] = -1;
  }
  rep(i,n){
    int x,y,v;
    tie(x,y,v) = items[i];
    x = mpX[x];
    y = mpY[y];
    items[i] = make_tuple(x,y,v);
  }
  sort(items.begin(),items.end());
  vector<ll> dp(n);
  rep(i,n){
    int x,y,v;
    tie(x,y,v) = items[i];
    if(x < 0 || y < 0)continue;
    dp[i] = maxim(0,y+1) + v;
    add(y,dp[i]);
  }
  ll ans = 0;
  rep(i,n){
    ans = max<ll>(ans,dp[i]);
  }
  cout << ans << endl;
}