#include <fstream>
using namespace std;

int main() {

    int i,N,New,Old;
    long long Sum;

    ifstream in("operatii.in");
    ofstream out("operatii.out");

    in>>N;

    for(i=1,Sum=0;i<=N;i++) {

        in>>New;
        Sum+=(New>Old?New-Old:0);
        Old=New;

        }

    out<<Sum<<'\n';

    in.close();
    out.close();

    return 0;

}