#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS
#endif
#include <fstream>
#include <cstring>
#include <algorithm>
#include <cmath>

using namespace std;

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

long long n, pre, x, rez;

int main()
{
	int i;

	fin >> n;
	pre = 0;
	for (i = 1; i <= n; i++)
	{
		fin >> x;
		rez += max((long long)0, x - pre);
		pre = x;
	}
	fout << rez << '\n';
	return 0;
}