#include <fstream>

using namespace std;

int n;
long long result;

int main()
{
    ifstream f ("operatii.in");
    int x, i, last = 0;
    f>>n;
    for (i=1; i<=n; i++)
    {
        f>>x;
        if (x > last)
            result += x-last;
        last = x;
    }
    f.close();
    ofstream g ("operatii.out");
    g<<result<<"\n";
    g.close();
    return 0;
}