#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 <valarray>
#include <limits>
#include <ranges>
namespace man {
constexpr inline void chmax(int64_t &a, const int64_t b) noexcept {
    if(a < b) {
        a = b;
    }
}
}
int main() {
    std::cin.tie(nullptr) -> sync_with_stdio(false);
    int n;
    std::cin >> n;
    std::valarray<int> a(n);
    for(auto &e: a) {
        std::cin >> e;
    }
    std::valarray<int64_t> dp(2);
    dp[1] = std::numeric_limits<int>::min();
    for(const auto &i: std::views::iota(0, n)) {
        std::valarray ndp = dp;
        man::chmax(ndp[0], dp[0]);
        man::chmax(ndp[0], dp[1] + a[i]);
        man::chmax(ndp[1], dp[1]);
        man::chmax(ndp[1], dp[0] - a[i]);
        dp.swap(ndp);
    }
    dump(dp);
    const auto ret = dp.max();
    if(ret == 0) {
        std::cout << a.min() << '\n';
        std::exit(0);
    }
    std::cout << ret << '\n';
}