#include <bits/stdc++.h>

using namespace std;

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

long long n, v[1000001], nr;

int main()
{
    f >> n;

    for(int i = 1; i <= n; i++)
        f >> v[i];

    for(int i = 0; i <= n; i++)
        if(v[i + 1] - v[i] > 0)
            nr += (v[i + 1] - v[i]);

    g << nr;

    return 0;
}