#include <fstream>

using namespace std;

ifstream in("operatii.in");
ofstream out("operatii.out");
long long n, ans;
int v[1000005];

int main()
{
    in>>n;

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

        if(v[i] > v[i-1])
        {
            ans += (v[i] - v[i-1]);
        }
    }

    out<<ans;

    return 0;
}