#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#ifdef local
#include <C++/core/io/debug_print.hpp>
#else
#define dump(...) void(0);
#endif

#include <iostream>
#include <vector>
#include <algorithm>
#include <ranges>
namespace man {

}
int main() {
    std::cin.tie(nullptr) -> sync_with_stdio(false);
    int n;
    std::cin >> n;
    std::vector<int> a(n);
    for(auto &e: a) {
        std::cin >> e;
    }
    std::vector dp(n + 1, std::vector(2, 0L));
    for(const auto &i: std::views::iota(0, n)) {
        dp[i + 1][1] = std::max(dp[i][1], dp[i][0] - a[i]);
        if(i == 0) {
            continue;
        }
        dp[i + 1][0] = std::max(dp[i][0], dp[i][1] + a[i]);
    }
    dump(dp);
    const auto ret = *std::ranges::max_element(dp.back());
    if(ret == 0) {
        std::cout << *std::ranges::min_element(a) << '\n';
        std::exit(0);
    }
    std::cout << ret << '\n';
}