#include <fstream>
using namespace std;

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

int main() {
    int N, last = 0, now;
    long long cnt = 0;
    in >> N;
    for(int i = 0; i < N; ++i) {
        in >> now;
        cnt += (last < now ? now - last : 0);
        last = now;
    }
    out << cnt << "\n";
    return 0;
}