#include <fstream>
using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
int c[1000001],i,n;
long long sol;
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)
    {
        fin>>c[i];
        if(c[i]>c[i-1])
            sol+=c[i]-c[i-1];
    }
    fout<<sol;
}