#include <bits/stdc++.h>
using namespace std;

int main( int argc, char *argv[] )
{
int i;
int N;
int iVal;
long long iOut;

	// 入力
	cin >> N;

	iOut = 0;
	for( i = 0; i < N; i++ )
	{
		cin >> iVal;
		if( iVal < 0 ) iVal = - iVal;

		if( iVal == 0 )
			continue;
		else if( iVal == 1 )
			iOut += 1;
		else
		{
			if( iOut == 0 || iOut == 1 )
				iOut += iVal;
			else
				iOut *= iVal;
		}
	}

	// 出力
	cout << iOut << endl;

	return 0;
}