#include "fish.h"
#include <vector>
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("trapv")

long long max_weights(int N, int M, std::vector<int> X, std::vector<int> Y,
                      std::vector<int> W) {
  vector<vector<int>> v;
  v.resize(N); 
  for (int i = 0 ; i < M ; i++){
    v[X[i]].push_back(W[i]); 
  }
  vector<int> u(N+1);
  for (int i = 0 ; i < N ; i++){
    //for (auto j : v[i]) cout << j << ' '; 
    if (!v[i].empty()) u[i+1] = v[i][0];
  }
  //cout << '\n';
  long long dp[N+1] = {};
  dp[1] = u[1];
  for (int i = 2 ; i <= 3 ; i++){
    dp[i] = max(dp[i-1] , dp[i-2] + u[i]); 
   // cout << i << ' ' << u[i] << ' ' << dp[i-1] << ' ' << dp[i-2] << '\n';
  }
  for (int i = 4 ; i <= N ; i++){
    dp[i] = max({dp[i-1] , dp[i-2] + u[i] , dp[i-4] + u[i-2] + u[i-1]});
  }
  return dp[N]; 
}