#include "fish.h"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
int n;
unordered_map<ll,ll> m, dp;
ll solve(int c, int p1, int p2){
if (c == n) return 0;
if (dp.find(c*100+(p1+1)*10+p2+1) != dp.end()) return dp[c*100+(p1+1)*10+p2+1];
ll cur = 0, res = 0;
for (int i=-1; i<max(n, 10); ){
//if (c == 4 && p1 == -1 && p2 == -1) cout << i << " " << cur << "\n";
res = max(res, cur+solve(c+1, i, p1));
i++;
if (c > 0 && p1 < i && (c == 1 || p2 < i)) cur += m[(c-1)*9+i];
if (c < n-1) cur += m[(c+1)*9+i];
if (c > 0 && p1 >= i) cur -= m[c*9+i];
}
//cout << c << " " << p1 << " " << p2 << " " << res << "\n";
return dp[c*100+(p1+1)*10+p2+1] = res;
}
ll max_weights(int N, int M, vector<int> X, vector<int> Y, vector<int> W){
n = N;
for (int i=0; i<M; i++) m[X[i]*9+Y[i]] = W[i];
return solve(0, 0, 0);
}
