#include <iostream>
#include <stdio.h>
using namespace std;

int bh[1010][1010] = {{0}};
int quan[1010];

int X[1010], Y[1010];

int minX = 2147483647, minY = 2147483647;

int ans = 0;

int N;

int dfs(int bianhao, int shangge){
	//上个为-1表示是根节点，否则为上一个的编號
	int fangxiang[4][2] = {{-1,0},{0,1},{1,0},{0,-1}};
	int dqX = X[bianhao] - minX + 1, dqY = Y[bianhao] - minY + 1;
	int res = quan[bianhao];
	for(int i = 0; i < 4; i++){
		int xinbh = bh[dqX + fangxiang[i][0]][dqY + fangxiang[i][1]];
		if(xinbh == 0 || xinbh == shangge) continue;
		int temp = dfs(xinbh, bianhao);
		if(temp > 0) res += temp;
	}
	if(res > ans) ans = res;
	return res;
}

int main() {
	scanf("%d",&N);
	for(int i = 1; i <= N; i++){
		scanf("%d%d%d", &X[i], &Y[i], &quan[i]);
		if(minX > X[i]) minX = X[i];
		if(minY > Y[i]) minY = Y[i];
	}
	for(int i = 1; i <= N; i++){
		bh[X[i]-minX+1][Y[i]-minY+1] = i;
	}

	dfs(1, -1);
	printf("%d\n", ans);

	return 0;
}