#include <fstream>

#define In "operatii.in"
#define Out "operatii.out"

using namespace std;

int main()
{
    int i, x , n, ult = 0,sol = 0;
    ifstream f(In);
    f>>n;
    for(i = 1;i <= n;i++)
    {
        f>>x;
        if(x>ult)
            sol += x - ult;
        ult = x;
    }
    f.close();
    ofstream g(Out);
    g<<sol<<"\n";
    g.close();
    return 0;
}