#include <fstream>

#define input "operatii.in"
#define output "operatii.out"
#define NMAX 1000005

using namespace std;

ifstream in(input);
ofstream out(output);

int N, sir[NMAX];

void Read_Data()
{
    in >> N;
    for(int i = 1; i <= N; i++)
        in >> sir[i];
}

void Solve()
{
    long long sol = 0;
    for(int i = 1; i <= N; i++)
    {
        if(sir[i - 1] < sir[i])
            sol += (long long)(sir[i] - sir[i - 1]);
    }
    out << sol << "\n";
}

int main()
{
    Read_Data();
    Solve();
    return 0;
}