#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int tempo_massimo (int n, int a[], int b[]) {

  int nt = 0, st = 0, ht = 0;
  for (int i = 0; i < n; ++i) {
    int nnt = max({nt, st, ht});
    int nst = max({nt, st, ht}) + a[i];
    int nht = nt + b[i];

    nt = nnt; st = nst; ht = nht;
  }

  return max({st, ht});
}

/*
int main() {

  ll n, k; cin >> n >> k;

  int a[n];
  for (int i = 0; i < n; ++i) cin >> a[i];

  cout << quadri(n, k, a) << '\n';
    
}
*/