#include <bits/stdc++.h>
#define ll long long
using namespace std ;
int n = 0 ;
ll a[405] ;
ll dp[405],vis[405] ;
ll bt(int pos)
{
if (pos == n)
return 0 ;
if (vis[pos] == 1)
return dp[pos] ;
ll res = bt(pos+1) + a[pos]+ a[pos+1] ;
if (pos < n-2 && pos > 0)
res = min(res,(bt(pos-1) + a[pos]+ a[pos-1])) ;
vis[pos] = 1 ;
dp[pos] = res ;
return res ;
}
int main()
{
cin >> n ;
for (int i = 0 ; i < n ; i++)
cin >> a[i] ;
ll x = bt(0) ;
cout << x << "\n" ;
return 0 ;
}
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