#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vll vector<ll>
#define all(x) begin(x),end(x)
const int N=1e5+10;
vll pre[N];
ll sz[N];
vll dp[N][3];
vll possible[N];
vector<pair<ll,ll>> values[N];
ll solve(ll&n,ll&m,vll&x,vll&y,vll&w)
{
ll ans=0;
for(int j=0;j<m;j++)
{
values[x[j]].push_back({y[j]+1,w[j]});
possible[x[j]].push_back(y[j]+1);
possible[x[j]+1].push_back(y[j]+1);
if(x[j]>0)
possible[x[j]-1].push_back(y[j]+1);
}
for(int i=0;i<=n;i++)
{
possible[i].push_back(0);
possible[i].push_back(n);
sort(begin(possible[i]),end(possible[i]));
sort(begin(values[i]),end(values[i]));
sz[i]=possible[i].size();
pre[i].resize(sz[i]+1,0);
ll sm=0;
int pp=0;
int rp=0;
for(auto&j:possible[i])
{
while(pp<values[i].size() and values[i][pp].first<=j)
{
sm+=values[i][pp].second;
pp++;
}
pre[i][rp]=sm;
rp++;
}
dp[i][0].resize(sz[i]+1,0);
dp[i][1].resize(sz[i]+1,0);
}
// for(int i=0;i<n;i++)
// for(int j=0;j<=n;j++)
// for(int k=0;k<2;k++)
// dp[i][j][k]=0;
for(int i=1;i<n;i++)
{
// ll sum=0;
ll mx1=-2e18;
ll mx2=-2e18;
ll mx11=0,mx22=0;
for(int k=0;k<sz[i];k++)
{
int hp=possible[i][k];
mx11=max(mx11,dp[i-1][0][k]);
auto index=lower_bound(all(possible[i-1]),hp)-begin(possible[i-1]);
mx1=max(mx1,dp[i-1][0][k]-pre[i-1][index]);
}
for(int k=0;k<sz[i];k++)
{
int hp=possible[i][k];
mx11=max(mx11,dp[i-1][1][k]);
auto index=lower_bound(all(possible[i]),hp)-begin(possible[i]);
mx1=max(mx1,dp[i-1][1][k]+pre[i][index]);
}
int pp=0;
for(auto&h:possible[i])
{
auto index=lower_bound(all(possible[i-1]),h)-begin(possible[i-1]);
dp[i][0][pp]=max(dp[i][0][pp],mx1+pre[i-1][index]);
dp[i][1][pp]=max(dp[i][1][pp],mx1+pre[i-1][index]);
dp[i][1][pp]=max(dp[i][1][pp],mx2-pre[i][pp]);
dp[i][0][pp]=max(dp[i][0][pp],mx11);
dp[i][0][pp]=max(dp[i][0][pp],mx22);
dp[i][1][pp]=max(dp[i][1][pp],mx11);
dp[i][1][pp]=max(dp[i][1][pp],mx22);
pp++;
}
}
for(int i=0;i<n;i++)
{
for(int j=0;j<sz[i];j++)
{
ans=max(ans,dp[i][0][j]);
ans=max(ans,dp[i][1][j]);
}
}
return ans;
}
long long max_weights(int N, int M, std::vector<int> X, std::vector<int> Y,std::vector<int> W)
{
ll n=N,m=M,ans=0;
vector<ll> x(all(X)),y(all(Y)),w(all(W));
return solve(n,m,x,y,w);
}
