#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
ll max_weights(int n, int m, vector<int> X, vector<int> Y, vector<int> W){
vector<vector<ll>> v(n, vector<ll>(n+1, 0));
for(int i = 0; i < m; i++) v[X[i]][Y[i]+1]+=W[i];
vector<vector<ll>> dp_up(n, vector<ll>(n+1, 0)), dp_down = dp_up,
dtu2 = dp_up;
vector<ll> dtu(n, 0);
vector<vector<ll>> pref(n, vector<ll>(n+1, 0));
for(int i = 0; i < n; i++) for(int j = 0; j <= n; j++){
if(j) pref[i][j] = pref[i][j-1];
pref[i][j]+=v[i][j];
}
for(int i = n-1; i >= 0; i--){
for(int j = 0; j <= n; j++){
if(i == n-1){
dp_down[i][j] = 0;
dp_up[i][j] = 0;
continue;
}
dp_up[i][j]-=pref[i][j];
dp_down[i][j]-=pref[i+1][n]-pref[i+1][j];
dp_up[i][j] = max(dp_up[i][j], pref[i][n]-pref[i][j]+dp_down[i+1][n]);
if(i+2 < n){
dp_down[i][j] = max(dp_down[i][j], dtu2[i+2][j]+pref[i+1][j]);
dp_down[i][j] = max(dp_down[i][j], dtu[i+2]-pref[i+1][j]);
dp_down[i][j] = max(dp_down[i][j], pref[i+1][n]-pref[i+1][j]+dp_down[i+2][n]);
}
}
if(i){
ll mx = 0;
for(int j = 0; j <= n; j++) mx = max(mx, pref[i-1][j]+dp_up[i][j]);
fill(dp_up[i-1].begin(), dp_up[i-1].end(), mx);
dtu[i] = mx;
mx = 0;
for(int j = 0; j <= n; j++) mx = max(mx, pref[i][n]-pref[i][j]+dp_down[i][j]);
fill(dp_down[i-1].begin(), dp_down[i-1].end(), mx);
for(int j = 0; j <= n; j++){
if(j) dtu2[i][j] = dtu2[i][j-1];
dtu2[i][j] = max(dtu2[i][j], dp_up[i][j]);
}
}
}
return max(*max_element(dp_up[0].begin(), dp_up[0].end()), *max_element(dp_down[0].begin(), dp_down[0].end()));
}
