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

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    
    int N;
    cin >> N;
    vector<ll> C(N);
    rep(i, 0, N) cin >> C[i];
    
    cout << abs(C[0]) + abs(C[0] - C[N - 1]) + abs(C[N - 1]) << '\n';
}