// operatii.cpp : Defines the entry point for the console application.
//

//#include "stdafx.h"
#include "fstream"
using namespace std;
int main()
{
	ifstream f("operatii.in");
	ofstream g("operatii.out");
	int nr;
	f>>nr;
	long long e;
	long long i,max=0,op=0;
	for(i=0;i<nr;i++)
	{
		f>>e;
		if(e>max)
			op=op+(e-max);
		max=e;
	}
	g<<op;
	return 0;
}