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

const long long INF = (1LL << 60);

int main() {
    int N;
    cin >> N;
    vector A(N, 0LL);
    for(int i = 0; i < N; i++) cin >> A[i];
    vector dp(N+1, vector(2, vector(2, -INF)));
    dp[0][0][0] = 0LL;
    for(int i = 0; i < N; i++) {
        for(int j = 0; j < 2; j++) {
            dp[i+1][j][0] = dp[i][j][0];
            dp[i+1][j][1] = max(dp[i][j][1], dp[i+1][j][1]);
            dp[i+1][1-j][1] = max(dp[i][j][0] + (j ? 1LL : -1LL) * A[i], dp[i+1][1-j][1]);
            dp[i+1][1-j][1] = max(dp[i][j][1] + (j ? 1LL : -1LL) * A[i], dp[i+1][1-j][1]);
        }
    }
    cout << max(dp[N][0][1], dp[N][1][1]) << endl;
    return 0;
}