https://codeforces.com/gym/580226/problem/I

#include<bits/stdc++.h>
using namespace std;
#define endl '\n'
#define lowbit(x)  x&(-x)
using ll = long long;
using pii = pair<int, int>;
const double PI = acos(-1);
const int N = 5e5 + 10;
const int mod = 1e9 + 7;
ll a[N];
void solve() {
	int n;cin>>n;
	ll sum=0;
	ll mi=1e18;//1e18来比较
	ll ma=-1e18;
	bool flag1=0,flag2=0;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		if(a[i]<0) flag1=1;
		if(a[i]>0) flag2=1;
		sum+=abs(a[i]);
		mi=min(mi,a[i]);
		ma=max(ma,a[i]);
	
	}
	if(n==1) {//要特判
		cout<<a[1];
		return;
	}
	if(flag1==1&&flag2==1){
		cout<<sum;
	}
	else if(flag1==1&&flag2==0){
	
		cout<<sum+2*ma;
	}
	else if(flag1==0&&flag2==1){
		cout<<sum-2*mi;
	}
	else cout<<0;
		
	
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr), cout.tie(nullptr);
	
	int T = 1;
//	cin>>T;
	while (T--) {
		solve();
	}
	
	return 0;
}