#include <iostream>

using namespace std;

int main()
{
	int N, numar, numar_prec = 0;
	
	long long rez = 0;
	
	freopen ("operatii.in", "r", stdin);
	freopen ("operatii.out", "w", stdout);
	
	scanf ("%d", &N);
	
	for (int i = 1; i <= N; ++i)
	{
		scanf ("%d", &numar);
		if (numar > numar_prec) rez += (numar - numar_prec);
		numar_prec =numar;
	}	
	
	printf ("%lld", rez);
	
	return 0;
}