#include <iostream>
#include <fstream>
#include <cstring>
#define int long long

using namespace std;

string filename = "operatii";

ifstream fin (filename + ".in");
ofstream fout (filename + ".out");

signed main()
{
    int n;
    fin>>n;
    int ans = 0;
    int x;
    int last;
    for(int i=1;i<=n;i++)
    {
        fin>>x;
        if(x>last)
            ans += (x - last);
        last = x;
    }
    fout<<ans;

}