#include <bits/stdc++.h>
#define ll long long
#define vt vector
#define pb push_back
#define ar array
#define all(x) (x).begin(), (x).end()
#define sz(x) (x).size()
using namespace std;
/*
## TAKE IT EASY ##
1. simplify
2. add new elements
3. brute force solution
4. optimize
5. start implementing
*/
// --- templates ---
// --- code ---
const int N = 3000 + 10, FLOW = 3;
ll dp[N][FLOW][N];
ll max_weights(int n, int m, vt<int> X, vt<int> Y, vt<int> W){
memset(dp, 0, sizeof dp);
int h = n + 5;
vt<vt<ll>> a(n + 5, vt<ll>(h));
for(int i = 0; i < m; i++){
a[X[i]][Y[i] + 1] = W[i];
}
for(int i = 0; i < n; i++){
for(int j = 1; j < h; j++){
a[i][j] += a[i][j - 1];
}
}
for(int i = 0; i < n; i++){
for(int flow = 0; flow < FLOW; flow++){
vt<ll> sufmax(h + 5), prefmax(h + 5);
if(i){
for(int h1 = h; h1 >= 0; h1--){
sufmax[h1] = max(sufmax[h1 + 1], dp[i - 1][flow][h1]);
}
prefmax[0] = dp[i - 1][flow][0];
for(int h1 = 1; h1 < h; h1++){
prefmax[h1] = max(prefmax[h1 - 1], dp[i - 1][flow][h1] - a[i - 1][h1] - (flow == 2 ? 0 : a[i][h1]));
}
}
for(int h2 = 0; h2 < h; h2++){
if(i == 0){
dp[i][1][h2] = max(dp[i][1][h2], a[i + 1][h2]);
}else{
if(flow == 0){
// h1 > h2
dp[i][0][h2] = max(dp[i][0][h2], sufmax[h2 + 1] + a[i + 1][h2] - a[i][h2]);
// h1 == h2
dp[i][1][h2] = max(dp[i][1][h2], dp[i - 1][flow][h2] + a[i + 1][h2] - a[i][h2]);
}else if(flow == 1){
// h1 > h2
dp[i][0][h2] = max(dp[i][0][h2], sufmax[h2 + 1] + a[i + 1][h2] - a[i][h2]);
// h1 <= h2
dp[i][1][h2] = max(dp[i][1][h2], prefmax[h2] + a[i + 1][h2] + a[i - 1][h2]);
}else{
// h1 > h2
dp[i][1][h2] = max(dp[i][1][h2], sufmax[h2 + 1] + a[i + 1][h2]);
// h1 <= h2
dp[i][1][h2] = max(dp[i][1][h2], prefmax[h2] + a[i + 1][h2] + a[i - 1][h2]);
}
}
if(i)
dp[i][2][h2] = max(dp[i - 1][0][h2], dp[i - 1][1][h2]);
}
}
}
ll ans = 0;
for(int flow = 0; flow < FLOW; flow++){
for(int h1 = 0; h1 < h; h1++){
ans = max(ans, dp[n - 1][flow][h1]);
}
}
return ans;
}
