#include <fstream>

using namespace std;
long long n, i, ant, crt, sol;
int main () {
    ifstream fin ("operatii.in");
    ofstream fout("operatii.out");

    fin>>n;
    ant = 0;
    for (i=1;i<=n;i++) {
        fin>>crt;
        if (crt > ant) {
            sol += (crt-ant);
        }
        ant = crt;
    }
    fout<<sol;
    return 0;
}