#include <bits/stdc++.h>
 
using namespace std;
#define ll long long
#define ull unsigned ll
#define all(x) x.begin(), x.end()
const ll MOD = 1e9 + 7;
const int MAX = 5000010;
int lastInc[MAX] = {};
 
ll a[100010], dp[100010][2];
int n;
ll F(int i, int isFlipped)
{
    if (i > n)
        return 0;
    if (dp[i][isFlipped])
        return dp[i][isFlipped];
    ll x = a[i];
    if (isFlipped)
        x = -x;
    ll y = x + F(i + 1, 0);
    ll z = -x + F(i + 1, 1);
    return dp[i][isFlipped] = max(y, z);
}
 
int main()
{
 
    cin >> n;
    for (size_t i = 1; i <= n; i++)
    {
        cin >> a[i];
    }
    cout << F(0, 0) << endl;
}

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