#include<bits/stdc++.h>
#pragma GCC optimize("-Ofast")
//#pragma GCC optimize("trapv")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.2,popcnt,abm,mmx,avx2,tune=native")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-funroll-loops")
#define I inline void
#define S struct
#define vi vector<int>
#define vii vector<pair<int,int>>
#define pii pair<int,int>
#define pll pair<ll,ll>
using namespace std ;
using ll = long long ;
using ld = long double ;
const int N = 5e5 + 7 , mod = 1e9 + 7 ;
const ll inf = 1e8 ;
// How interesting!
int n;
int a[N];
int dp[305][205][205] ;
int solve(int i , int x , int y){
if(~dp[i][x][y])
return dp[i][x][y] ;
if( i == n + 2 )
return 0 ;
int ret = 0 ;
int A = a[i-2] - x ;
int B = a[i-1] - y ;
int C = a[i] ;
for(int j = min({A , B , C}) ;j <= a[i] ;j ++){
int mn = min(j , min({A , B , C}) ) ;
int mn2 = min(B - mn , C - mn) ;
if(mn + mn2 < j)
break ;
mn2 = min(mn2 , j - mn) ;
ret = max(ret ,2 * mn + mn2 + solve(i+1 , y + j , j ) ) ;
}
return dp[i][x][y] = ret;
}
int main(){
ios_base::sync_with_stdio(0) ;
cin.tie(0) ;
memset(dp , -1 , sizeof dp) ;
cin >> n;
int ans = 0 ;
for(int i = 0 ;i < n;i++){
cin >> a[i + 2] ;
ans += a[i + 2] * 3;
}
cout<< ans - solve(2 , 0 , 0);
return 0 ;
}
