#include <fstream>
using namespace std;

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

int main() {
    int n;
    cin >> n;
    long long answer = 0;
    int last, current;
    for (int i = 1; i <= n; i++) {
        cin >> current;
        if (i != 1 && current < last)
            answer += (last - current);
        last = current;
    }
    answer += current;
    cout << answer << "\n";
    return 0;
}