#include <fstream>
#include <iostream>
using namespace std;

int n;
int a[1000001];

void read() {
    int i;
    ifstream f("operatii.in");
    f >> n;
    for (i = 1; i <= n; i++)
        f >> a[i];
    f.close();
}

long long nr;

void solve() {
    int i, x = 0;
    for (i = 1; i <= n; i++)
        if (a[i] > x) {
            nr += a[i] - x;
            x = a[i];
        }
        else x = a[i];
}

void output() {
    ofstream g("operatii.out");
    g << nr;
    g.close();
}

int main() {
    read();
    solve();
    output();
    return 0;
}