#include <iostream>
#include <fstream>

using namespace std;

int n, i, j, v[1000005], rez, nr, mx;

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

    fin >> n;
    fin >> v[1];
    v[n+1] = 0;
    nr = 1;
    for (i = 1; i <= n+1; i++)
    {
        fin >> v[i];
        if (v[i] > v[i-1])  rez += v[i]-v[i-1];
    }
    fout << rez << "\n";
}