#include <fstream>
using namespace std;

int main() {
    ifstream fin("operatii.in");
    ofstream fout("operatii.out");

    int N;
    fin >> N;

    long long ans = 0;

    int prev, x;
    fin >> prev;

    ans = prev;

    for (int i = 2; i <= N; i++) {
        fin >> x;

        if (x > prev)
            ans += x - prev;

        prev = x;
    }

    fout << ans;

    return 0;
}