#include<iostream>
#include<fstream>
#include<algorithm>

using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
long long n, aux, i, a, sum;

int main()
{
    fin>>n;aux=0;
    for(i=1;i<=n;i++)
    {
        fin>>a;
        if(aux<a)
        {
            sum+=a-aux;
            aux=a;
        }
        if(aux>a)
            aux=a;
    }
    fout<<sum;
    fin.close();
    fout.close();
    return 0;
}