#include<bits/stdc++.h>
#define rep(x,y,z) for(int x=y;x<=z;x++)
#define drep(x,y,z) for(int x=y;x>=z;x--)
#define ull unsigned long long
#define ll long long
using namespace std;
inline int read()
{
	int x=0;bool flag=1;char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-')flag=0;ch=getchar();}
	while(ch>='0'&&ch<='9') {x=(x<<3)+(x<<1)+ch-'0';ch=getchar();}
	if(flag) return x;
	return ~(x-1);
} 
inline void write(int x)
{
	if(x<0) {x=~(x-1);putchar('-');}
	if(x>9) write(x/10);
	putchar(x%10+'0');
}
/////////////////////////////////// 
const int N=1e3+50;
int nc;
struct nin
{
	int x;
	int y;
	int val;
}s[N];
int hd[N];
struct qxx
{
	int ar;
	int val;
	int nx;
}a[N];
int aj;
int ans=-(1<<30);
inline void ADD(int x,int y)
{
	a[++aj].nx=hd[x];
	a[aj].ar=y;
	a[aj].val=a[y].val;
	hd[x]=aj;
}
struct DFS
{
	int se;//包括本身
	int de;//不包括本身 
}b[N]; 
void dfs(int cl)
{
	b[cl].se=s[cl].val;
	for(int i=hd[cl];i;i=a[i].nx)
	{
		dfs(a[i].ar);
		if(b[a[i].ar].se>0) b[cl].se+=b[a[i].ar].se;
		b[cl].de=max(b[cl].de,max(b[a[i].ar].de,b[a[i].ar].se));
	}
	ans=max(ans,max(b[cl].de,b[cl].se));//更新答案 
}
int main()
{
    freopen("subset.in","r",stdin);
	freopen("subset.out","w",stdout);
    nc=read();
    rep(i,1,nc)
    {
    	s[i].x=read(),s[i].y=read(),s[i].val=read();
		rep(o,1,i-1)
		{
			if(s[o].x==s[i].x-1&&s[o].y==s[i].y) ADD(o,i);
			else if(s[o].x==s[i].x+1&&s[o].y==s[i].y) ADD(o,i);	
			else if(s[o].x==s[i].x&&s[o].y==s[i].y-1) ADD(o,i);
			else if(s[o].x==s[i].x&&s[o].y==s[i].y+1) ADD(o,i);
		}	
	}
	dfs(1);
	write(ans),putchar(10);
    return 0;
}