#include<iostream>
#include<iomanip>
#include<vector>
#include<algorithm>
#include<map>
#include<queue>
#include<string.h>
#include<math.h>
using namespace std;

#define ll long long
#define inf 1e9
#define MAX 100000

ll b[20], res = 0, tmp = inf, a[20];

int main(){
	for (ll i = 0; i < 20; i++)cin >> b[i];
	for (ll k = 0; k < 2; k++) {
		for (ll i = 0; i < 20; i++) a[i] = b[i];
		res = 0;
		if (k == 1) { a[0] ^= 1; a[1] ^= 1; res = 1; }
		for (ll i = 0; i < 19; i++) {//最后一个不能单独拱
			if (a[i] == 1) {
				res++; a[i] ^= 1;
				if (i + 1 < 20) a[i + 1] ^= 1;
				if (i + 2 < 20) a[i + 2] ^= 1;
			}
		}
		if (res < tmp&&a[19] == 0) tmp = res;
	}
	cout << tmp << endl;
}