#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    ifstream f("operatii.in");
    ofstream g("operatii.out");

    int N, a, b;
    long long sol;

    f >> N >> a;

    sol = a;

    for ( int i = 2; i <= N; ++i )
    {
        f >> b;

        if ( b > a ) sol += b - a;

        a = b;
    }

    g << sol << "\n";

    return 0;
}