#include "fish.h"
#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e17;
typedef long long ll;
const ll MOD = (ll)1e9+7;
#define P pair
#define S second
#define F first
#define pb push_back
#define V vector
#define all(v) v.begin(), v.end()
long long max_weights(int N, int M, std::vector<int> X, std::vector<int> Y,std::vector<int> W) {
V<V<ll>>pref(N+1,V<ll>(N+1));
for (int i=0;i<M;i++) {
pref[X[i]][Y[i]+1]+=W[i];
}
for (int i=0;i<N;i++) {
for (int j=1;j<=N;j++) {
pref[i][j]+=pref[i][j-1];
}
}
ll dp[N][N+1][2];
ll maxp[N][N+2][2];
ll maxs[N][N+2][2];
memset(dp,0,sizeof(dp));
memset(maxp,0,sizeof(maxp));
memset(maxs,0,sizeof(maxs));
ll maxd=0;
for (int i=1;i<N;i++) {
for (int j=0;j<=N;j++) {
for (int g=0;g<=N;g++) {
dp[i][j][0]=max(dp[i][j][0],max(maxs[i-1][j][0]-pref[i][j],maxp[i-1][j][1]));
dp[i][j][1]=max(dp[i][j][1],max(maxd,max(maxp[i][j][0]+pref[i-1][j],maxs[i][j][1])));
}
}
for (int j=0;j<=N;j++) {
maxd=max(maxd,dp[i][j][0]);
}
for (int j=N;j>=0;j--) {
maxs[i][j][0]=max(maxs[i][j+1][0],max(dp[i][j][0],dp[i][j][1])+pref[i+1][j]);
maxs[i][j][1]=max(maxs[i][j+1][1],dp[i][j][1]);
}
maxp[i][0][1]=max(dp[i][0][1],dp[i][0][0]);
maxp[i][0][0]=dp[i][0][1]-pref[i][0];
for (int j=1;j<=N;j++) {
maxp[i][j][1]=max(maxp[i][j-1][1],max(dp[i][j][0],dp[i][j][1]));
maxp[i][j][0]=max(maxp[i][j-1][0],dp[i][j][1]-pref[i][j]);
}
}
ll ans=0;
for (int i=0;i<=N;i++) {
ans=max(ans,max(dp[N-1][i][0],dp[N-1][i][1]));
}
return ans;
}
