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

int main()
{
    ifstream cin ("operatii.in");
    ofstream cout ("operatii.out");
    int v[1000000], s = 0;
    long long n;
    cin >> n;
    for (int i=1; i<=n; i++){
        cin >> v[i];
        if (v[i] > v[i-1])
            s += v[i] - v[i-1];
    }
    cout << s;
    return 0;
}