#include <bits/stdc++.h>

using namespace std;
using ll = long long;
// #define int ll
using PII = pair<ll, ll>;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()

template<typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }

template<typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) {
  return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type
fill_v(T &t, const V &v) { t=v; }
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t, const V &v ) { for(auto &e:t) fill_v(e,v); }

template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a){
  out<<'('<<a.first<<','<<a.second<<')'; return out;
}
template<typename T>
istream& operator >> (istream& is, vector<T>& vec){
  for(T& x: vec) {is >> x;} return is;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
  out<<'['; for(T i: a) {out<<i<<',';} out<<']'; return out;
}

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0}; // DRUL
const int INF = 1<<30;
const ll LLINF = 1LL<<60;
const ll MOD = 1000000007;

signed main(void)
{
  cin.tie(0);
  ios::sync_with_stdio(false);

  ll n;
  cin >> n;
  vector<ll> a(n);
  REP(i, n) cin >> a[i];
  vector<ll> b(a);
  FOR(i, 1, n) b[i] += b[i-1];

  ll ans = LLINF;
  // ぐ
  {
    vector<ll> dp(n);
    if(a[0] == 0) dp[0] = 0;
    else if(a[0]%2) dp[0] = 1;
    else dp[0] = 0;
    FOR(i, 1, n) {
      if(a[i] == 0) dp[i] = min(dp[i-1] + 2, b[i-1]);
      else if(a[i]%2) dp[i] = min(dp[i-1] + 1, b[i-1] + 1);
      else dp[i] = min(dp[i-1], b[i-1]);
    }

    REP(i, n) chmin(ans, dp[i] + b[n-1] - b[i]);
//    cerr << ans << endl;
  }

  // き
  {
    vector<ll> dp(n);
    if(a[0] == 0) dp[0] = 0;
    else if(a[0]%2) dp[0] = 0;
    else dp[0] = 1;
    FOR(i, 1, n) {
      if(a[i] == 0) dp[i] = min(dp[i-1] + 1, b[i-1]);
      else if(a[i]%2) dp[i] = min(dp[i-1], b[i-1]);
      else dp[i] = min(dp[i-1]+1, b[i-1]+1);
    }

    REP(i, n) chmin(ans, dp[i] + b[n-1] - b[i]);
//    cerr << ans << endl;
  }

  // ぐき
  {
    vector<vector<ll>> dp(n, vector<ll>(2, LLINF));
    if(a[0] == 0) dp[0][0] = 0;
    else if(a[0]%2) dp[0][0] = 1;
    else dp[0][0] = 0;
    FOR(i, 1, n) REP(j, 2) {
        if(a[i] == 0) chmin(dp[i][0], min(dp[i-1][0] + 2, b[i-1]));
        else if(a[i]%2) chmin(dp[i][0], min(dp[i-1][0] + 1, b[i-1] + 1));
        else chmin(dp[i][0], min(dp[i-1][0], b[i-1]));

        if(a[i] == 0) chmin(dp[i][1], min(dp[i-1][j] + 1, b[i-1]));
        else if(a[i]%2) chmin(dp[i][1], min(dp[i-1][j], b[i-1]));
        else chmin(dp[i][1], min(dp[i-1][j]+1, b[i-1]+1));
      }

//    cout << dp << endl;

    REP(i, n) REP(j, 2) chmin(ans, dp[i][j] + b[n-1] - b[i]);
//    cerr << ans << endl;
  }

  // きぐ
  {
    vector<vector<ll>> dp(n, vector<ll>(2, LLINF));
    if(a[0] == 0) dp[0][0] = 0;
    else if(a[0]%2) dp[0][0] = 0;
    else dp[0][0] = 1;
    FOR(i, 1, n) REP(j, 2) {
        if(a[i] == 0) chmin(dp[i][1], min(dp[i-1][j] + 2, b[i-1]));
        else if(a[i]%2) chmin(dp[i][1], min(dp[i-1][j] + 1, b[i-1] + 1));
        else chmin(dp[i][1], min(dp[i-1][j], b[i-1]));

        if(a[i] == 0) chmin(dp[i][0], min(dp[i-1][0] + 1, b[i-1]));
        else if(a[i]%2) chmin(dp[i][0], min(dp[i-1][0], b[i-1]));
        else chmin(dp[i][0], min(dp[i-1][0]+1, b[i-1]+1));
      }

//    cout << dp << endl;

    REP(i, n) REP(j, 2) chmin(ans, dp[i][j] + b[n-1] - b[i]);
//    cerr << ans << endl;
  }

  // ぐきぐ
  {
    vector<vector<ll>> dp(n, vector<ll>(3, LLINF));
    if(a[0] == 0) dp[0][0] = 0;
    else if(a[0]%2) dp[0][0] = 1;
    else dp[0][0] = 0;
    FOR(i, 1, n) REP(j, 3) {
      if(a[i] == 0) chmin(dp[i][0], min(dp[i-1][0] + 2, b[i-1]));
      else if(a[i]%2) chmin(dp[i][0], min(dp[i-1][0] + 1, b[i-1] + 1));
      else chmin(dp[i][0], min(dp[i-1][0], b[i-1]));

      if(a[i] == 0 && j<=1) chmin(dp[i][1], min(dp[i-1][j] + 1, b[i-1]));
      else if(a[i]%2 && j<=1) chmin(dp[i][1], min(dp[i-1][j], b[i-1]));
      else if(j<=1) chmin(dp[i][1], min(dp[i-1][j]+1, b[i-1]+1));

      if(a[i] == 0 && j>=1) chmin(dp[i][2], min(dp[i-1][j] + 2, b[i-1]));
      else if(a[i]%2 && j>=1) chmin(dp[i][2], min(dp[i-1][j] + 1, b[i-1] + 1));
      else if(j>=1) chmin(dp[i][2], min(dp[i-1][j], b[i-1]));
    }

//    cout << dp << endl;

    REP(i, n) REP(j, 3) chmin(ans, dp[i][j] + b[n-1] - b[i]);
//    cerr << ans << endl;
  }

  cout << ans << endl;

  return 0;
}

Measured memory_bytes: 16344