#include "fish.h"
#include <bits/stdc++.h>
#define R(a) for (int i = 0; i < a; ++i)
#define RR(a) for (int j = 0; j < a; ++j)
using namespace std;
typedef long long ll;
typedef vector<int> vi;
// (idx, i - 1, i)
ll dp[100'005][2][2];
ll max_weights(int N, int M, vi X, vi Y, vi W) {
vector<ll> val(N + 1);
R(M) val[X[i]] = W[i];
dp[0][0][1] = dp[0][1][1] = val[1];
for (int i = 1; i < N; ++i) {
dp[i][0][0] = max(dp[i - 1][1][0], dp[i - 1][0][0]);
dp[i][0][1] = max(dp[i - 1][1][0], dp[i - 1][0][0] + val[i - 1]) + val[i + 1];
dp[i][1][0] = max(dp[i - 1][0][1], dp[i - 1][1][1]);
dp[i][1][1] = max(dp[i - 1][0][1], dp[i - 1][1][1]) + val[i + 1];
}
return max({dp[N-1][0][0], dp[N-1][0][1], dp[N-1][1][0], dp[N-1][1][1]});
}
