#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)

template <typename T> bool chmin(T &x, T y) {
	return x > y ? (x = y, true) : false;
}
template <typename T> bool chmax(T &x, T y) {
	return x < y ? (x = y, true) : false;
}

struct IOST {
	IOST() {
		ios::sync_with_stdio(false);
		cin.tie(nullptr);
		cout << fixed << setprecision(20);
	}
} IOST;

int main(){
	int n;
	cin>>n;
	vector<int> a(n);
	rep(i,0,n) cin>>a[i];
	int ans=0;
	if(a.front()<0) ans+=abs(a.front())*2;
	if(a.back()>0) ans+=a.back()*2;
	cout<<ans<<"\n";
}