#include<bits/stdc++.h>
#include<atcoder/all>
#define chmin(x,y) (x) = min((x),(y))
#define chmax(x,y) (x) = max((x),(y))
using namespace std;
using namespace atcoder;
using ll = long long;
const ll mod = 998244353;
using mint = modint998244353;
using Graph = vector<vector<int>>;

const vector<int> dx = {1,0,-1,0}, dy = {0,1,0,-1};

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

	
  if(N == 1){
  	cout << -A[0] << endl;
  	return 0;
  }
    
  // solve
  const ll INF = 1LL<<61;
  vector<vector<ll>> dp(N+1,vector<ll>(3,-INF));
  dp[0][0] = 0;
  for(int i = 0; i < N; i++){
    if(dp[i][0] > -INF){
      chmax(dp[i+1][0],dp[i][0]);
      chmax(dp[i+1][1],dp[i][0] - A[i]);
    }
    if(dp[i][1] > -INF){
      chmax(dp[i+1][1],dp[i][1]);
      chmax(dp[i+1][2],dp[i][1] + A[i]);
    }
    if(dp[i][2] > -INF){
      chmax(dp[i+1][2],dp[i][2]);
      chmax(dp[i+1][1],dp[i][2] - A[i]);
    }
  }
  
  // output
  cout << max(dp[N][2],dp[N][1]) << endl;
}