/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.06.04 21:48:26
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    int n;cin >> n;
    constexpr long long LLINF = 1e18 + 1;
    ll nax = 0;
    ll nin = 0;
    cin >> nax;
    nin = nax;
    for (int i = 0; i < n-1; i++) {
        int a; cin >> a;
        ll tmp_nax = max({nax+a,nin+a,nax-a,nin-a,nax*+a,nin*a});
        ll tmp_nin = min({nax+a,nin+a,nax-a,nin-a,nax*+a,nin*a});
        nax = tmp_nax;
        nin = tmp_nin;
    }
    cout << nax << endl;
    return 0;
}