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

using ll=long long;
#include<atcoder/modint>
using namespace atcoder;
using mint=modint998244353;


int main(){
	
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	ll N;
	cin>>N;
	ll P=0,Q=0;
	for(int i=0;i<N;i++){
		ll C;
		cin>>C;
		(C>0?P:Q)=max((C>0?P:Q),abs(C));
	}
	cout<<(P+Q)*2<<endl;
}