import std.stdio, std.string, std.conv, std.range, std.array, std.algorithm;
import std.uni, std.math, std.container, std.typecons, std.typetuple;
import core.bitop, std.datetime;

immutable long inf = 1L<<60;

long ans = -inf;

void main() {
    int N = readln.chomp.to!int;
    auto a = readln.split.map!(to!long).array;

    dfs(N, a, 1, a[0]);

    writeln(ans);
}

void dfs(int N, long[] a, int idx, long value) {
    if (idx == N) {
        ans = max(ans, value);
        return;
    }

    dfs(N, a, idx + 1, value + a[idx]);
    dfs(N, a, idx + 1, value - a[idx]);
    dfs(N, a, idx + 1, value * a[idx]);
}


void readVars(T...)(auto ref T args)
{
    auto line = readln.split;
    foreach(ref arg ; args){
        arg = line.front.to!(typeof(arg));
        line.popFront;
    }
    if(!line.empty){
        writeln(line);
        throw new Exception("args num < input num");
    }
}