#include <bits/stdc++.h>

using namespace std;

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

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

int n;
vector<int> a;

int main() {
	cin >> n;
	REP(i, n) {
		int in;
		scanf("%d", &in);
		a.push_back(in);
	}
	
	int necnt = 0, one = 0;
	REP(i, n) {
		if (a[i] < 0) {
			if (i != 0 && a[i] == -1) one++;
			else necnt++;
		}
	}
	
	int ma = -INF;
	FOR(i, 1, n) if (a[i] < 0) chmax(ma, a[i]);
	
	if (necnt % 2 == 0) ma = -INF;
	
	ll ans = 0;
	
	REP(i, n) {
		if (i != 0 && a[i] == ma) {
			ans += -a[i];
			ma = -INF;
		}
		else if (i != 0 && a[i] == -1) {
			ans++;
		}
		else if (a[i] == 1) {
			ans++;
		}
		else if (a[i] != 0) {
			if (ans == 0) ans += abs(a[i]);
			else ans *= abs(a[i]);
		}
	}
	
	cout << ans << endl;
	
	return 0;
}