#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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