#include <fstream>

using namespace std;

int main ()
{
    int N;
    long long S;
    ifstream fin ("operatii.in");
    fin >> N;
    long long a, b;
    fin >> a;
    S = a;
    for (int i = 1; i < N; i++)
    {
        fin >> b;
        if (a < b) S += b - a;
        a = b;
    }
    fin.close ();
    ofstream fout ("operatii.out");
    fout << S;
    fout.close ();
    return 0;
}