#include <algorithm>
#include <vector>
#include <iostream>
using namespace std;

int tempo_massimo(int N, int a[], int b[]) {
    vector<long long> dp(N,0);
  dp[0]=max(a[0],b[0]);
  for(int i=1;i<N;i++){
    int aus=0;
    if(i>1) aus=dp[i-2];
    if(a[i]<b[i]){
      if(dp[i-1]+a[i]>aus+b[i]){
        dp[i]=dp[i-1]+a[i];
      }else dp[i]=aus+b[i];
    }else dp[i]=dp[i-1]+a[i];
  }
  
  return dp[N-1];
}
/*
int main(){
    int n=0;
    cin>>n;
  int a[n];
  int b[n];
  for(int i=0;i<n;i++){
    cin>>a[i]>>b[i];
  }
  cout<<tempo_massimo(n,a,b);
 return 0;   
}*/