#include <iostream>
#include <fstream>

using namespace std;

const char iname[] = "operatii.in";
const char oname[] = "operatii.out";

ifstream fin(iname);
ofstream fout(oname);

long long mx, ct, i, a[1000005], n;

int main()
{
	fin >> n;
	for(i = 1; i <= n; i ++)
		fin >> a[i];

	for(i = 1; i <= n; i ++)
		if(a[i - 1] < a[i])
			ct = ct + a[i] - a[i - 1];
	fout << ct << "\n";
	return 0;
}