#include <algorithm>
#include <iostream>
#include <memory.h>
#include <iterator>
#include <cassert>
#include <fstream>
#include <iomanip>
#include <cstdlib>
#include <bitset>
#include <vector>
#include <cstdio>
#include <string>
#include <queue>
#include <deque>
#include <cmath>
#include <ctime>
#include <stack>
#include <set>
#include <map>

using namespace std;

const int N = (int)5000 + 10;
const int INF = (int)1e9 + 10;

int n;
int a[N], dp[N];

int main ()
{
    //freopen("input.txt" , "r" , stdin);
    //freopen("output.txt" , "w" , stdout);
    ios_base::sync_with_stdio(false);

    cin >> n;
    for(int i = 1; i <= n; ++i) {
        cin >> a[i];
    }

    a[0] = INF;
    a[n + 1] = INF;
    for(int i = 1 ; i <= n ; ++i) {
        dp[i] = INF;
    }
    dp[0] = 0;
    int mn = INF;
    for(int i = 1 ; i <= n ; ++i){
        dp[i] = a[i] + mn;
        mn = min(mn, dp[i - 1] - a[i]);
    }
    cout << dp[n];



    return 0;
}