#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

ll dp[200005][2][2];

int main()
{
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i,n) cin >> a[i];
    // vector<vector<ll>> dp(n+1, vector<ll>(2, -1e18));
    rep(i,n+1)rep(k,2)rep(j,2) dp[i][j][k] = -1e18;
    dp[0][0][1] = 0;
    rep(i,n) {
        dp[i+1][1][1] = max(dp[i+1][1][1], dp[i][1][0]+a[i]);
        dp[i+1][1][0] = max(dp[i+1][1][0], dp[i][1][1]-a[i]);
        dp[i+1][1][1] = max(dp[i+1][1][1], dp[i][0][0]+a[i]);
        dp[i+1][1][0] = max(dp[i+1][1][0], dp[i][0][1]-a[i]);
        rep(k,2){
            dp[i+1][k][0] = max(dp[i+1][k][0], dp[i][k][0]);
            dp[i+1][k][1] = max(dp[i+1][k][1], dp[i][k][1]);
        }
    }
    dbg(dp);
    cout << max(dp[n][1][0], dp[n][1][1]) << endl;
    return 0;
}