#include "bits/stdc++.h"
using namespace std;
int main(void){
    // Here your code !
    int n,a,ans;
    cin >> n >> ans;
    while(--n)
    {
        cin >> a;
        
        if(a < 0) ans -= a;
        else if (a == 1) ans += a;
        else ans *= a;
    }
    cout << ans << endl;
}