#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
	int N;
	cin >> N;
	vector<ll> A(N);
	for(int i=0; i<N; i++){
		cin >> A[i];
	}

	vector able(N+1, vector<bool>(2, true));
	vector dp(N+1, vector<ll>(2, LLONG_MIN));
	able[1][0] = false;
	dp[1][1] = -A[0];

	for(int i=1; i<N; i++){
		if(able[i][0]){
			dp[i+1][0] = max(dp[i+1][0], dp[i][0]);
			dp[i+1][1] = max(dp[i+1][1], dp[i][0] - A[i]);
		}

		if(able[i][1]){
			dp[i+1][1] = max(dp[i+1][1], dp[i][1]);
			dp[i+1][0] = max(dp[i+1][0], dp[i][1] + A[i]);
		}
	}

	cout << max(dp[N][0], dp[N][1]) << endl;

	return 0;
}