#include <iostream>
#include <iomanip>
#include <algorithm>
#include <bitset>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <cmath>
#include <time.h>
#include <random>
#include <string>
#include <cassert>
#include <vector>
#include <ostream>
#include <istream>
#include <stack>
#include <deque>
#include <queue>
#include <functional>
#include <chrono>
#include <stack>

using namespace std;

#define int long long
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define pii pair<int, int>
#define ld long double

ostream& operator<< (ostream &a, const vector<int> &b) {
    for (auto k : b) cout << k << " ";
    return a;
}

istream& operator>> (istream& a, pii& b) {
    cin >> b.first >> b.second;
    return a;
}

ostream& operator<< (ostream& a, const pii& b) {
    cout << "{" << b.first << ", " << b.second << "}";
    return a;
}

template <typename T1, typename T2> inline void chkmin(T1 &x, const T2 &y) {if (x > y) x = y;}
template <typename T1, typename T2> inline void chkmax(T1 &x, const T2 &y) {if (x < y) x = y;}


#ifdef LOCAL
    #define dbg(x) cout << #x << " : " << (x) << "\n";
    const int INF = 1e18;
    // const int mod = 2600000069;
    // const int p = 10;
    // const ld PI = 3.1415926535;
#else
    #define dbg(x)
    const int INF = 1e18;
    // const int mod = 2600000069;
    // const int p = 179;
    // const ld PI = 3.1415926535;
#endif

// #pragma GCC optimize("Ofast,no-stack-protector")
// #pragma GCC target("sse,sse2,sse3,sse3,sse4")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC optimize("fast-math")
// #pragma GCC target("avx2")  
// #pragma GCC optimize("section-anchors")
// #pragma GCC optimize("profile-values,profile-reorder-functions,tracer")
// #pragma GCC optimize("vpt")
// #pragma GCC optimize("rename-registers")
// #pragma GCC optimize("move-loop-invariants")
// #pragma GCC optimize("unswitch-loops")
// #pragma GCC optimize("function-sections")
// #pragma GCC optimize("data-sections")

mt19937 gen(chrono::high_resolution_clock::now().time_since_epoch().count());

const int MAXN = 2e5 + 10;

int n;
int a[MAXN], dp[MAXN][3], pref[MAXN];

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        dp[i][0] = dp[i][1] = dp[i][2] = INF;
    }
    pref[0] = a[0];
    for (int i = 1; i < n; i++) {
        pref[i] = pref[i - 1] + a[i];
    }
    if (a[0]) {
        dp[0][0] = a[0] & 1;
        dp[0][1] = (a[0] & 1) ^ 1;
        dp[0][2] = a[0] & 1;
    } else {
        dp[0][0] = dp[0][1] = dp[0][2] = 0;
    }
    for (int i = 1; i < n; i++) {
        if (a[i] == 0) {
            chkmin(dp[i][0], pref[i - 1]);
            chkmin(dp[i][1], pref[i - 1]);
            chkmin(dp[i][2], pref[i - 1]);
            chkmin(dp[i][0], dp[i - 1][0] + 2);
            chkmin(dp[i][1], dp[i - 1][0] + 1);
            chkmin(dp[i][1], dp[i - 1][1] + 1);
            chkmin(dp[i][2], dp[i - 1][0] + 2);
            chkmin(dp[i][2], dp[i - 1][1] + 2);
            chkmin(dp[i][2], dp[i - 1][2] + 2);
        } else {
            chkmin(dp[i][0], pref[i - 1] + (a[i] & 1));
            chkmin(dp[i][1], pref[i - 1] + ((a[i] & 1) ^ 1));
            chkmin(dp[i][2], pref[i - 1] + (a[i] & 1));
            chkmin(dp[i][0], dp[i - 1][0] + (a[i] & 1));
            chkmin(dp[i][1], dp[i - 1][1] + ((a[i] & 1) ^ 1));
            chkmin(dp[i][1], dp[i - 1][0] + ((a[i] & 1) ^ 1));
            chkmin(dp[i][2], dp[i - 1][0] + (a[i] & 1));
            chkmin(dp[i][2], dp[i - 1][1] + (a[i] & 1));
            chkmin(dp[i][2], dp[i - 1][2] + (a[i] & 1));
        }
    }
    int ans = INF;
    int sum = 0;
    for (int i = n - 1; i >= 0; i--) {
        chkmin(ans, sum + min(dp[i][0], min(dp[i][1], dp[i][2])));
        sum += a[i];
    }
    cout << ans;
}
/*

*/  

Measured memory_bytes: 8064