#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    ifstream fin("operatii.in");
    ofstream fout("operatii.out");

    int n, x, sum, cx=0;
    fin >> n;
    sum=0;
    for(int i=1; i<=n; i++){
        fin >> x;
        if(x>cx){
            sum=sum+x-cx;
        }
        cx=x;
    }
    fout << sum;
    return 0;
}