#include <fstream>
using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");

int main()
{
    int n;
    fin >> n;
    long long last = 0, sum = 0;
    for (int i = 1; i <= n; ++i) {
        int x;
        fin >> x;
        (x >= last)? sum += x - last: true;
        last = x;
    }
    fout << sum;
    return 0;
}