#include <bits/stdc++.h>
// #include "homecoming.h"
using namespace std;
typedef long long ll;
ll solve(int n, int k, int *a, int *b){
ll dp[2 * n + 10] = {};
ll pa[2 * n + 10], pb[2 * n + 10];
pa[0] = pb[0] = 0;
for (int i = 1; i <= 2 * n; i ++){
pa[i] = pa[i - 1] + a[(i - 1) % n];
pb[i] = pb[i - 1] + b[(i - 1) % n];
}
ll ans = pa[n] - pb[n];
for (int i = 1; i <= n; i ++){
dp[i] = 0;
ll mx = 0;
for (int j = i + 1; j < i + n; j ++){
dp[j] = dp[j - 1];
if (j - k < i) continue;
mx = max(mx, dp[j - k] - pa[j - k] + pb[j - k]);
ll val = pa[i - k + 1] - pb[i];
dp[j] = max(dp[j], mx + val);
}
ans = max(ans, dp[i + n - 1]);
}
return ans;
}
// int main(){
// int a[3] = {40, 80, 100};
// int b[3] = {140, 0, 20};
// cout << solve(3, 2, a, b) << endl;
// }
