#include<bits/stdc++.h>
#define point pair<int,int> 
#define x first
#define y second
using namespace std;
const int N=4005;
int n,f[N],ans,cnt;
map<point,int> mp;
int hd[N],e[N<<1],nt[N<<1],idx;
bool vis[N];
int w[N];
point p[N];
int d[5][2]={0,1,0,-1,1,0,-1,0};
inline void add(int x,int y)
{
	nt[++idx]=hd[x],hd[x]=idx,e[idx]=y;
}
void dp(int nw)
{
	vis[nw]=1;
	f[nw]=w[nw];
	for(int i=hd[nw];i;i=nt[i])
		if(!vis[e[i]])
		{
			dp(e[i]);
			f[nw]=max(f[nw],f[e[i]]+f[nw]);
		}
	ans=max(ans,f[nw]);
	return ;
}
int main()
{
	freopen("subset.in","r",stdin);
	freopen("subset.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;++i)
	{
		scanf("%d%d%d",&p[i].x,&p[i].y,&w[i]);
		mp[p[i]]=++cnt;
	}
	for(int i=1;i<=n;++i)
		for(int j=0;j<4;++j)
			if(mp.count((point){p[i].x+d[j][0],p[i].y+d[j][1]}))
				add(mp[p[i]],mp[(point){p[i].x+d[j][0],p[i].y+d[j][1]}]),add(mp[(point){p[i].x+d[j][0],p[i].y+d[j][1]}],mp[p[i]]);
	dp(1);
	printf("%d\n",ans);
	return 0;
}