#include <fstream>

using namespace std;

int N;
int v[1000010];
int S = 0;

void Citire ()
{
    ifstream fin ("operatii.in");
    fin >> N;
    for (int i = 0; i < N; i++)
    {
        fin >> v[i];
    }
    fin.close ();
}

void Business ()
{
    S = v[0];
    for (int i = 1; i < N; i++)
    {
        if (v[i - 1] < v[i]) S += v[i] - v[i - 1];
    }
}

void Scriere ()
{
    ofstream fout ("operatii.out");
    fout << S;
    fout.close ();
}

int main ()
{
    Citire ();
    Business ();
    Scriere ();
    return 0;
}