#include <cstdio>
#ifdef DEBUG
#define D(X) X
#else
#define D(X)
#endif
#include <bits/stdc++.h>
#define F first
#define S second
#define ll long long
#define pi 3.14159265359
#define pub push_back
#define pob pop_back
//#include <fish.h>
using namespace std;
const int INF = 1000 * 1000 * 1000;
const int mod = 1000 * 1000 * 1000 + 7;
ll max_weights(int n, int m, vector<int> x, vector<int> y, vector<int> w)
{
vector<vector<ll>> cnt(n, vector<ll>(n+1, 0));
for(int i=0; i<m; i++) {
cnt[x[i]][y[i]+1] = w[i];
}
for(int j=0; j<n; j++) {
for(int i=1; i<=n; i++) {
cnt[j][i] += cnt[j][i-1];
}
}
vector<vector<int>> fish(n);
for(int i=0; i<m; i++) {
fish[x[i]].pub(y[i]);
}
vector<ll> dp(n+1);
dp[n] = 0;
vector<vector<ll>> dp2(3, vector<ll>(n+1, 0)), mx1(3, vector<ll>(n+1, 0)), mx2(3, vector<ll>(n+1, 0));
int bin = 0;
for(int i=n-1; i>=0; i--) {
dp[i] = dp[i+1];
if(i<n-1) {
for(int j=0; j<=n; j++) {
ll cur = cnt[i][j];
cur += max(mx1[(bin-2+3)%3][j], mx2[(bin-2+3)%3][j] - cnt[i+1][j]);
dp[i] = max(dp[i], cur);
dp[i] = max(dp[i], dp[i+2] + cnt[i+1][n] - cnt[i+1][j]);
}
}
if(i==0) {
break;
}
for(int j=0; j<=n; j++) {
dp2[bin][j] = max(mx1[(bin-1+3)%3][j], mx2[(bin-1+3)%3][j]); //if(i==n-2) cout<<dp2[bin][j]<<endl;
}
mx1[bin][0] = dp2[bin][0];
for(int j=1; j<=n; j++) {
mx1[bin][j] = max(mx1[bin][j-1], dp2[bin][j]); //if(i==n-1) cout<<mx1[bin][j]<<endl;
}
mx2[bin][n] = 0;
for(int j=n-1; j>=0; j--) {
mx2[bin][j] = max(mx2[bin][j+1], dp2[bin][j] + cnt[i-1][j]); //if(i==n-1) cout<<mx2[bin][j]<<endl;
}
bin = (bin+1)%3; //cout<<dp[i]<<endl;
}
return dp[0];
}
