#include <iostream>
using namespace std;

int main() {
	int a[20];
	for(int i = 0; i < 20; i++){
		cin >> a[i];
	}
	int x[20];
	int res = 21;
	int cnt = 0;
	for(x[0] = 0; x[0] <= 1; x[0]++){
		cnt = x[0];
		x[1] = (a[0]+x[0])%2;
		cnt += x[1];
		for(int i = 2; i < 20; i++) {
			x[i] = (x[i-1]+x[i-2]+a[i-1])%2;
			cnt += x[i];
		}
		if((x[18]+x[19]+a[19])%2 == 0 && cnt < res){
			res = cnt;
		}
	}
	cout << res;
	return 0;
}