#include <bits/stdc++.h>
#include "homecoming.h"
using namespace std;
const long long INF = 1e16;
const int MAX_N = 2e6;
const int MAX_SGT = 4e6 + 1;
struct SegTree {
vector<long long> segTree, lazy;
void init( int n ) {
segTree.resize( 4 * n );
lazy.resize( 4 * n );
for ( int v = 0; v < 4 * n; v++ ) {
segTree[v] = -INF;
lazy[v] = 0;
}
}
void propag( int v, int l, int r ) {
segTree[v] += lazy[v];
if ( l != r ) {
lazy[v * 2 + 1] += lazy[v];
lazy[v * 2 + 2] += lazy[v];
}
lazy[v] = 0;
}
void update( int v, int l, int r, int lu, int ru, long long x ) {
propag( v, l, r );
if ( l > ru || r < lu )
return;
if ( lu <= l && r <= ru ) {
lazy[v] = x;
propag( v, l, r );
return;
}
int mid = (l + r) / 2;
update( v * 2 + 1, l, mid, lu, ru, x );
update( v * 2 + 2, mid + 1, r, lu, ru, x );
segTree[v] = max( segTree[v * 2 + 1], segTree[v * 2 + 2] );
}
long long query( int v, int l, int r, int lq, int rq ) {
propag( v, l, r );
if ( l > rq || r < lq )
return -INF;
if ( lq <= l && r <= rq )
return segTree[v];
int mid = (l + r) / 2;
return max( query( v * 2 + 1, l, mid, lq, rq ), query( v * 2 + 2, mid + 1, r, lq, rq ) );
}
};
SegTree dp;
long long solve( int n, int k, int a[], int b[] ) {
long long ans = 0;
for ( int l = 0; l <= k && n * l <= 500000; l++ ) {
dp.init( n + l + 1 );
dp.update( 0, 0, n + l, n + l, n + l, INF );
for ( int i = n - 1; i >= 0; i-- ) {
if ( i >= l ) {
long long dpii = 0;
dpii = dp.query( 0, 0, n + l, i + 1, n + l ) - dp.query( 0, 0, n + l, i, i );
dp.update( 0, 0, n + l, i, i, dpii );
}
dp.update( 0, 0, n + l, i + 1, n + l, -b[i] );
dp.update( 0, 0, n + l, i + k, n + l, a[i] );
}
ans = max( ans, dp.query( 0, 0, n + l, 0, n + l ) );
}
return ans;
}
