//空の数列はNG <-- 見落としていましたorz
#include <iostream>
#include <algorithm>
#include <vector>
#define rep(i, n) for(i = 0; i < n; i++)
#define int long long
using namespace std;

void chmax(int &a, int b) { a = max(a, b); }

int INF = 1e+15;
int n;
int a[200000];
int dp[200001][2];

signed main() {
	int i, j;

	cin >> n;
	rep(i, n) cin >> a[i];
	rep(i, n + 1) rep(j, 2) dp[i][j] = -INF;
	rep(i, n) dp[i + 1][1] = -a[i];
	
	rep(i, n) {
		rep(j, 2) {
			if (dp[i][j] == -INF) continue;
			chmax(dp[i + 1][j], dp[i][j]);
			int mul = (j == 0) ? -1 : 1;
			chmax(dp[i + 1][!j], dp[i][j] + a[i] * mul);
		}
	}

	cout << max(dp[n][0], dp[n][1]) << endl;
	return 0;
}