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

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

const int N_max = 1000002;

int v[N_max];

long long ans;

int N;

int main()
{
    int i;

    in >> N;

    for(i = 1; i <= N; i++) in >> v[i];

    for(i = 1; i <= N; i++)
        if(v[i] > v[i - 1]) ans += v[i] - v[i - 1];

    out << ans;

    return 0;
}