#include <bits/stdc++.h>

using namespace std;

int n;

int main()
{
    ifstream fin ("operatii.in");
    ofstream fout ("operatii.out");
    fin >> n;
    int prev = 0;
    long long ans = 0;
    int elm;
    for(int i = 1; i <= n; i++)
    {
        fin >> elm;
        ans += max(0, elm - prev);
        prev = elm;
    }
    fout << ans << "\n";
    return 0;
}