// UUID: e9e62c72-adec-4e63-85d1-52d10797ad9c
#include <bits/stdc++.h>
#include <vector>
using namespace std;

int main() {
	int n;
	cin>>n;

vector<long long>h(n);
vector<long long> dp(n);
//cout<<" 'n' erteke: "<<n<<"\n";
for(int i=0;i<n;i++)
{

    cin >> h[i];
    //cout<<" h lefutott: "<< i <<"-szer \n";
   
}

dp[0]=h[0];
dp[1]=h[1]+h[0];
//dp[2]=h[2];
//dp[3]=abs((h[3]-h[2]))+dp[2];
//cout<<"dp[1] es dp[2] eleme: "<<dp[1]<<" "<<dp[2]<<"\n";

for(int i=2;i<n;i++)
{
    //n+=min(dp[i-1]+abs(h[i]-h[i-1]), dp[i-2]+abs(h[i]-h[i-2]));
    dp[i] = min(dp[i-1], (dp[i-2] )) + h[i];
    //cout<<"A dontes a dp[i]-edik eleme lesz: "<<dp[i]<<"\n";
}

cout<<dp[n-1]<<"\n";


}