$555$，只有 $0~\textrm{Pts}$，太惨了 QAQ

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N=4e3+10;
int n,m,k,t,x,y,v,head=0,tail=-1;
int a[N][N],dp[N][N],q[N];
signed main()
{
	scanf("%lld %lld %lld %lld",&n,&m,&k,&t);
	for(int i=1;i<=k;i++)
	{
		scanf("%lld %lld %lld",&x,&y,&v);
		a[x][y]=v;
	}
	for(int i=1;i<=m;i++)dp[1][i]=a[1][i];
	for(int i=2;i<=n;i++)
	{
		head=0,tail=-1;
		for(int j=1;j<=t*2;j++)
		{
			while(dp[i-1][j]>=dp[i-1][q[tail]] && head<=tail)--tail;
			q[++tail]=j;
		}
		for(int j=1;j<=m-t*2+1;j++)
		{
			dp[i][j]=dp[i-1][q[head]]+a[i][j];
			while(dp[i-1][j+t*2]>=dp[i-1][q[tail]] && head<=tail)--tail;
			q[++tail]=j+t*2;
			while(q[tail]-q[head]>2*t+1)++head;
		}
		if(q[tail]-q[head]>=2*t+1)++head;
		for(int j=m-t*2+2;j<=m;j++)
		{
			dp[i][j]=dp[i-1][q[head]]+a[i][j];
		}
	}
	int ans=-2e9;
	for(int i=1;i<=m;i++)ans=max(ans,dp[n][i]);
	printf("%lld\n",ans);
	return 0;
}