#include <bits/stdc++.h>
#define DAU  ios::sync_with_stdio(false); fin.tie(0); fout.tie(0);
#define PLEC fin.close(); fout.close(); return 0;
using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
int n, x, y;
int64_t res;
int main()
{
    DAU
    fin >> n;
    for (int i = 1; i <= n; ++i)
    {
        fin >> y;
        if (x < y)
            res += (y - x);
        x = y;
    }
    fout << res;
    PLEC
}