#include<bits/stdc++.h>
#define rep(i,a,...) for(int i = (a)*(strlen(#__VA_ARGS__)!=0);i<(int)(strlen(#__VA_ARGS__)?__VA_ARGS__:(a));++i)
#define per(i,a,...) for(int i = (strlen(#__VA_ARGS__)?__VA_ARGS__:(a))-1;i>=(int)(strlen(#__VA_ARGS__)?(a):0);--i)
#define foreach(i, n) for(auto &i:(n))
#define pii pair<int, int>
#define pll pair<long long, long long>
#define all(x) (x).begin(), (x).end()
#define bit(x) (1ll << (x))
using ll = long long;
//const ll MOD = (ll)1e9+7;
const ll MOD = 998244353;
const int INF = (ll)1e9+7;
const ll INFLL = (ll)1e18;
using namespace std;
template<class t>
using vvector = vector<vector<t>>;
template<class t>
using vvvector = vector<vector<vector<t>>>;
template<class t>
using priority_queuer = priority_queue<t, vector<t>, greater<t>>;
template<class t, class u> bool chmax(t &a, u b){if(a<b){a=b;return true;}return false;}
template<class t, class u> bool chmin(t &a, u b){if(a>b){a=b;return true;}return false;}
#ifdef DEBUG
#define debug(x) cout<<"LINE "<<__LINE__<<": "<<#x<<" = "<<x<<endl;
#else
#define debug(x) (void)0
#endif

namespace templates{
  ll modpow(ll x, ll b){
    ll res = 1;
    while(b){
      if(b&1)res = res * x % MOD;
      x = x * x % MOD;
      b>>=1;
    }
    return res;
  }

  ll modinv(ll x){
    return modpow(x, MOD-2);
  }

  bool was_output = false;
  template<class t>
  void output(t a){
    if(was_output)cout << " ";
    cout << a;
    was_output = true;
  }
  void outendl(){
    was_output = false;
    cout << endl;
  }
  ll in(){
    ll res;
    scanf("%lld", &res);
    return res;
  }

  template<class t>
  istream& operator>>(istream&is, vector<t>&x){
    for(auto &i:x)is >> i;
    return is;
  }

  template<class t, class u>
  istream& operator>>(istream&is, pair<t, u>&x){
    is >> x.first >> x.second;
    return is;
  }

  template<class t>
  void in(t&x){
    cin >> x;
  }

  template<class t>
  t in(){
    t res; cin >> res; return res;
  }

  template<class t>
  void out(t x){
    cout << x;
  }

  template<class t>
  vector<t> sorted(vector<t> line,function<bool(t,t)> comp=[](t a,t b){return a<b;}){
    sort(line.begin(),line.end(),comp);
    return line;
  }

  template<class t>
  vector<t> reversed(vector<t> line){
    reverse(line.begin(),line.end());
    return line;
  }
}

using namespace templates;

int main(){
  int n = in();
  vector<ll> line(n);
  vector<ll> sum(n);
  foreach(i,line)i=in();
  sum[0] = line[0];
  rep(i,n-1){
    sum[i+1]=sum[i]+line[i+1];
  }
  function<ll(int,int)> func1 =
    [&](int place,int back)->ll{
      if(place==n)return 0;
      static vvector<ll> dp(n+1,vector<ll>(2,-1));
      ll &it = dp[place][back];
      if(it>=0)return it;
      it = (sum[n-1]-sum[place]) + ((back and (line[place]&1))?1:0);
      if(line[place]&1){
        chmin(it,1+func1(place+1,true));
      }else{
        chmin(it,max(0LL,2-line[place]) + func1(place+1,true));
      }
      if(!back){
        if(line[place]&1){
          chmin(it,func1(place+1,false));
        }else{
          chmin(it,1+func1(place+1,false));
        }
      }
      return it;
    };
  function<ll(int,int)> func2 =
    [&](int place,int back)->ll{
      if(place==-1)return 0;
      static vvector<ll> dp(n+1,vector<ll>(2,-1));
      ll &it = dp[place][back];
      if(it>=0)return it;
      it = (place?sum[place-1]:0)  + ((back and (line[place]&1))?1:0);
      if(line[place]&1){
        chmin(it,1+func2(place-1,true));
      }else{
        chmin(it,max(0LL,2-line[place]) + func2(place-1,true));
      }
      if(!back){
        if(line[place]&1){
          chmin(it,func2(place-1,false));
        }else{
          chmin(it,1+func2(place-1,false));
        }
      }
      return it;
    };
  ll ans = INFLL;
  rep(i,1,n){
    chmin(ans,func2(i-1,false)+func1(i,false));
  }
  chmin(ans,func1(0,false));
  chmin(ans,func2(n-1,false));
  cout << ans << endl;
  return 0;
}


Measured memory_bytes: 47232